Design Aspects in Augmented Reality Games - Online

Design Aspects in Augmented Reality Games
MARKUS WEILGUNY
DIPLOMARBEIT
eingereicht am
Fachhochschul-Masterstudiengang
D I G I TA L E M E D I E N
in Hagenberg
im Juni 2006
Erklärung
Hiermit erkläre ich an Eides statt, dass ich die vorliegende Arbeit selbstständig und ohne fremde Hilfe verfasst, andere als die angegebenen Quellen und
Hilfsmittel nicht benutzt und die aus anderen Quellen entnommenen Stellen
als solche gekennzeichnet habe.
Hagenberg, am 20. Juni 2006
Markus Weilguny
ii
Table of Contents
Acknowledgment
vi
Kurzfassung
vii
Abstract
viii
Introduction
1
1.Foreword
1
2.Notations used in this Thesis
3
3.Structure of the Thesis
4
Appreciating Games
5
4.What is a Game? 5.A very concise History of Computer Games
6.A General Definition of Games
7.Self-Sufficiency and Interdependency
8.Goals
9.Rules
5
5
10
11
12
14
10. What is Game Design? 11. The Science of Game Design
12. Playability
13. Creating a Unique and Emotionally Appealing Game
17
17
18
19
14. Influences on Playability in Game Design
15. Story
16. The Player’s Impact on the Game
17. Challenges
18. Difficulty
19. Long-Term Motivation through Unpredictability
20. Diversity of Challenges
21. Action and Reaction
22. Strategy and Exploration
23. Playfulness and Goal-Orientation
24. The Meaning of Virtual Life
23
23
25
28
28
29
30
31
31
32
35
iii
25. Environmental Factors in Game Design
26. Rewards
27. Complex Computation and Simple Rules
28. Incentives & Details
29. Toys
38
41
44
46
49
Augmented Games
51
30. Augmented Reality
31. What is Augmented Reality? 32. Game Design for Augmented Reality
33. Development of Augmented Reality Applications
34. Interactive Art
35. Conceptualizing a Game: Buffet Battle
51
51
52
53
55
58
36. Design Aspects
37. Space
38. The Dimensions of a Game World
39. The Physical Dimension
40. The Temporal Dimension
41. The Social Dimension
42. Input and Feedback
43. Levels of Interaction
44. Choosing a suitable Technology
45. Input Dimensions
46. Physical Input
47. Haptic Input
48. Audio Input
49. Feedback Dimensions
50. Visual Feedback
51. Audio Feedback
52. Haptic Feedback
61
61
64
64
67
69
75
77
79
81
83
85
89
92
93
104
108
The Design of Neon Racer
111
53. Design of a Racing Game
54. Idea
55. Goals and Rules
56. The Racing Game Genre
57. Setting
58. The Player’s Impact on the Game
111
111
113
113
114
115
iv
59. Visual and Audio Content
60. 2D Graphics
61. Incentives
62. Bonus Items
63. Motion Lines and Skid-marks
64. Sound Design
65. Limitations of Audio Feedback
116
116
117
117
119
120
121
66. The Setup Space
67. The Physical Dimension
68. Hardware Setup
69. Area of the Game
70. Relationship between Real and Virtual
71. The Temporal Dimension
72. The Social Dimension
73. Number of Players and Participants
74. Competitiveness
75. Private and Public Space
76. Social Interaction
122
122
122
123
123
123
124
124
125
125
125
77. Input and Feedback
78. Control of the Vehicles with Gamepads
79. Interaction with Real Objects
80. Tracking
81. Game Engine and Obstacle Detection System
82. Physics
127
127
127
127
129
130
83. Conclusion
132
84. Team and Acknowledgments
134
Conclusion
135
85. Current Chances for Augmented Games
135
86. Developing Game Concepts
136
87. Technology and Emotion: Ideals of Future Games?
138
Contents of the DVD
141
Bibliography
142
v
Acknowledgment
In recent years, I have spent more and more time creating Augmented Reality
games. This would not have been possible without my colleagues who shared
the pleasure of creating new applications on the edge of technology and entertainment. My thanks goes out to all teammates, colleagues, supervisors,
employers and professors who invested their hard work, endured my creativity and gave valuable feedback. Naturally, none of it would have been as
meaningful and satisfying without the support of my family and friends. They
shape my world.
vi
Kurzfassung
Diese Arbeit beschäftigt sich mit Design Aspekten, die relevant für die Entwicklung von Augmented Reality Spielen sind. Es werden Einflüsse auf
Spiele, welche die reale und die virtuelle Welt vereinen, untersucht. Das Ziel
der Überlegungen dieser Arbeit ist es, dem Spieler eine vielseitige, unterhaltsame und langfristig ansprechende Erfahrung zu vermitteln. Diese Arbeit untersucht die Tiefe von Game Design anhand physischer Spiele, z.B. Brettspiele,
Kartenspiele, Sportspiele, Kinderspiele, ebenso wie virtueller Computerspiele.
Game Design von Computerspielen formuliert viele Design Aspekte, die auch
in Augmented Reality Spielen ihre Gültigkeit behalten. Zusätzlich bieten diese
noch die Möglichkeit, die physische Umgebung und die soziale Interaktion zu
planen. Spieler können unterschiedliche Eingabegeräte und Anzeigen benutzen, sich in ihrer realen Umgebung bewegen, mit Mitspielern kommunizieren und sich so in das Spielgeschehen einbringen.
Neben zahlreichen Beispielen zeigt diese Arbeit abschließend anhand von
“Neon Racer”, einem Augmented Reality Rennspiel, eine mögliche, praktische
Umsetzung der vorgestellten Game Design Aspekte.
vii
Abstract
This thesis investigates design aspects which are relevant to Augmented Reality games. Entertainment applications that incorporate both the real and virtual world are subject to intricate design considerations. The complexity of
designing an emotional and satisfying experience for the player is explored.
To obtain an understanding of the parameters that influence the player’s experience of a game, board games, card games as well as computer games and
interactive installations are analyzed.
Numerous design aspects for virtual games are contained in the science of
computer game design. Most of these guidelines are also valid in augmented
games. Augmented Reality offers additional options to design physical and
social interaction. For instance, the player can influence a game with unique
input and feedback devices. Furthermore, he can move around in the real
world and interact with other participants.
In conclusion, the findings of this thesis on design aspects in Augmented
Reality games are outlined on the example of Neon Racer, an augmented racing game.
viii
1. Introduction
Chapter 1
Introduction
1.1. Foreword
Computer games have fascinated me since I was a little child. The earliest
games I remember playing are the single-color versions of Diamonds, Frogger
and Space Invaders. I did not like playing challenging or scary games myself
then. Rather, I would sit next to my elder brother and watch him play and
progress through the puzzles of Zak McCracken, the mazes of Ultima Underworld or the perils of Rosella.
Sometimes, our entire family would sit around the “486” with a hard-copy of a
King’s Quest walkthrough and argue about when to type in ‘jump’ to prevent
Rosella from drowning in a frog-ridden swamp or from being dragged away
by gargoyles. Together, we used to ponder our next actions and face numerous
deadly corners in these early adventure games. Dyna Blaster and Worms even
allowed us to play together simultaneously. Later, technology made LAN play
possible, and we could enjoy get-togethers where we played games like Duke
Nukem or Dungeon Keeper.
Beside computer games, real world games, too, were an important part of my
life from childhood to adolescence. Board games, social games and toys provided learning opportunities and fun, and they shaped my understanding of
the world. Through Monopoly, Cops and Robbers, Punch and Judy, Lego and
Playmobil, I grasped social behavior, explored fantasy worlds, and practiced
my motor-skills.
Playing off-screen games is a physical experience that involves both body and
mind. When playing computer games you only have to move the mouse or
1
Introduction
press some keys. In addition, the social aspect is often used as an argument
against computer games, in which the focus of attention lies solely on the
screen and not on people. In real world games the physical space is shared
with your partners, so social interaction becomes more immediate and intimate than in computer games. Especially my teachers often expressed the fear
that computer games might produce generations of physically weak, lonely
and socially handicapped children and adolescents.
I will not be the judge of these arguments. One possible solution out of the
dilemma of a computer-loving generation with supposedly too little physical
exercise and too many pseudo-social encounters is to be found in “Augmented Reality” (AR) games. AR provides the opportunity to integrate the
advantages of both computer games and classical off-screen games. A wide
range of stunning technologies bridge the gap between the real and the virtual
and allow the user to interact with both worlds (Benford, 2005). The world of
AR games is enriched by the social aspects of traditional board games. The
gaming experience is enhanced by tangible interfaces and augmented reality
can even encourage physical activity.
The symbiosis of physical and virtual games offers exciting new ways for the
design of games. Augmented Reality research has definitely redefined the
possibilities of creating applications for entertainment (Piekarski, 2002),
learning and communication (Figure 1.1). By putting both classical and computer games together, a modern, player-oriented and pervasive gaming environment can be created. In the long run, AR might even evolve a new generation of games that create new experiences and genres that, so far, could only
be imagined.
Figure 1.1: Augmented Reality could create a new generation of games
by enriching the real world with virtual information.
2
Introduction
1.2. Notations Used in this Thesis
Most expressions which are uncommon or used in a different manner from
every-day language are described in detail at the point at which they are introduced.
In general, the term “the player“ refers to any person who plays a game. Even
though augmented reality is especially suitable for multi-user interaction, the
singular form is used to convey that the individual is the center of attention
for the game designer. In this thesis, the term encompasses every possible individual player.
The term “the user“ is employed to describe people who interact with an interactive installation which is not strictly a game. A definition of games which
seems suitable for an augmented reality setting is given in Chapter 2, Section 1
“What is a Game?”.
“Augmented Reality“ (AR) is commonly defined as the enhancement of real,
physical surroundings with virtual information (see Chapter 3, Section 1
“Augmented Reality”). The term is used often and is either spelled in lowercase letters or used as an abbreviation.
The titles of games begin with a capital letter and are set in italics to distinguish them without the use of apostrophes, e.g. Chess, Quest for Glory.
To improve readability, this thesis uses the masculine form wherever both
male and female persons are referred to. For instance, “he” and “the player”,
refer to both male and female participants of a game. This was done simply to
enhance readability and does not reflect player demographics in any way.
3
Introduction
1.3. Structure of the Thesis
In order to find ways of enhancing playability in augmented games, it is first
necessary to look at the way we experience games in general, be it board
games or computer games, since augmented reality games seem to encompass
elements of all existing kinds. Secondly, an overview of augmented reality
environments illustrates possible modes of interaction. By analyzing these interaction techniques, their emotional effects on the player can be better appreciated and targeted. The correlation between the elements of a game and the
player’s emotional reactions can then be used to design a unique experience in
an AR game.
The first part, “Appreciating Games“, briefly presents the essentials of game
design. It outlines the fundamental principles of designing an experience for
the player and demonstrates the vast variety of influences game design has on
this experience. The thoughts and emotions that a player experiences are
shaped by the story, the rules, the visuals and the challenges of a game.
The second part, “Augmented Games“, illustrates existing augmented reality
games and interfaces. It shows different directions that the development of
hardware and software can take to incorporate the real world and humanbody interaction. The chapter illustrates the range of options that are available
today, by presenting sample AR applications and how they handle the design
and partitioning of space, the use of social control mechanisms in multi-player
games, etc. The applications presented should convey an idea of how to utilize
these new technologies for game design.
Ultimately, “The Design of Neon Racer“ presents a sample application of game
design in augmented reality. The theoretical principles of this thesis are analyzed in their application during the development of Neon Racer, an AR racing
game.
The literature on game design ranges from psychology to programming artificial intelligence (AI). This thesis does not claim to be a complete description of
all conventions and theories, but aims at creating an awareness of the versatile
design issues and options that are available to the developers of AR games.
This brief description of game design and AR games should merely illustrate
some of the most important design principles.
4
2. Appreciating Games
Chapter 2
Appreciating Games
The following chapter deals with the nature of games and briefly presents the
essentials of game design. Games are utterly versatile and they include social,
psychological and emotional factors. The variety of games gives the game designer a broad range of actions to shape a unique and emotional experience
for the player.
2.1. What is a Game?
2.1.1. A Very Concise History of Computer Games
Early computer games were rather simple like Tennis, Pong and Space Invaders.
The available hardware limited graphics and programs to a few kilobytes.
Later, adventure games with their hand-pixeled backgrounds bloomed (Figure
2.1). It was the time of Roger Wilco, King’s Quest, Indiana Jones and Guybrush
Threepwood. These adventures made far more complex interaction possible.
The player had to work through a vast amount of options, which usually involved going through illogical puzzles and avoiding countless dangers and
improbable death threats. As a prime example, flushing the toilet in Larry
caused a clog and drowned poor Larry instantly. Adventure games employed
narrative and suspense in a manner quite like traditional storytelling, as described by Campbell (1972). The games extended a narrative sequence with so
many challenges and decisions that the player felt as though he himself was
capable of determining the outcome of the otherwise linear story. The final
victory of the virtual protagonist at “The End” appeared to be a victory of the
player himself.
5
Appreciating Games
Figure 2.1: Early adventures like King’s Quest offered hand-crafted
backgrounds and complex stories.
Technology evolved further and utilized advanced visual and audio content.
Interestingly, the story and interaction of games became simpler again. This is
illustrated by the hugely successful Diablo, Quake, Starcraft and Unreal Tournament (Figure 2.2).
Figure 2.2: Action games like Diablo elevated a simple idea into a
well-balanced gaming experience.
These games were no less entertaining than their adventure-game ancestors,
but they offered a very different experience. They managed to refine a simple
set of rules, e.g. running around and shooting down opponents in order to
6
Appreciating Games
win, into a well-balanced and enjoyable game. In this respect they were quite
unlike earlier games, in which numerous possibilities had to be explored at
every intersection.
Strategy games also evolved from early ancestors into the well-established
genre of today. The turn-based Civilization stands out as a cornerstone in the
development of games that include exploration, managing resources and
combat. It was followed by countless variations of the topic: Strategy games
taking place on earth and in outer space, in the past and the far future.
The rise of real-time strategy games was initially marked by the popular Dune 2,
followed by Command and Conquer, Warcraft 2 and Starcraft (Figure 2.3). They
sported mathematically complex, tactical systems with numerous units,
buildings, factions and special abilities in a real-time environment.
Figure 2.3: Real-time strategy games like Command and Conquer let the player
control complex, dynamic systems.
With the rise of online games and improved artificial intelligence, the trend
towards adventure games has returned. However, they are now combined
with the popular elements of action games. This has created an actionadventure genre, which offers the light-hearted and superficial slaying of
7
Appreciating Games
monsters, combined with exploration and character development, but still
lacks much of the refinement of yesteryears’ adventure games (Figure 2.4).
Figure 2.4: The trend of online games such as Guild Wars is to combine
adventure games with action and strategy elements.
Parallel to fully featured games, the market for casual entertainment has
grown tremendously. The so-called casual games such as card games, quizzes
and puzzles, do not demand long-term commitment but can be played for a
mere couple of minutes for entertainment (Figure 2.5). Tetris and Arkanoid
have spawned masses of descendant puzzle-games and reaction-based games.
They can be played online, on handhelds such as the Gameboy, on mobile
phones and photoplay consoles at malls and cinemas, addressing players in a
greater variety of environments than fully featured games do (Rollings, 2003).
Casual games do not have a story filled with revelations and twists, neither do
they require the player to learn complicated rules, but they can be grasped in a
matter of minutes. Therefore, casual games are ideally suited for entertainment at fast-paced and stressful times, or at public places where players usually have little time and attention.
Augmented reality games can be found in similar surroundings at exhibitions,
shopping malls and conferences. Thus, AR can utilize game design considerations that have been proven by generations of casual games.
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Appreciating Games
Figure 2.5: Casual games such as Zuma create a light-hearted and superficial
entertainment experience based on simple interaction.
Casual games focus on a single, simple idea, similar to games like Diablo. This
idea is supported by well-balanced rules, atmospheric background imagery
and an intuitive interface, mostly point-and-click. It is these simple rules and
interfaces that allow players to learn the game quickly. Players feel in command of the game from the start and yet they are constantly challenged to
further increase their skills. Bit by bit, players can become experts at what they
do and feel satisfied at every step of the way.
Small step-by-step victories can create addiction: There is always another colored stone to click, another knob to turn. This phenomenon, by the way, is also
an important part of fully featured games such as World of Warcraft, in which
there is always another item to deliver, another enemy to defeat and another
weapon to craft. Most people who have played this kind of computer games,
will, at some point, have uttered something like, “just one more round”.
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Appreciating Games
2.1.2. A General Definition of Games
A definition of games has been attempted by numerous philosophers. However, a clear definition might be impossible. Wittgenstein (1953) remarked that
a general definition of games would deter from their richness and diversity.
Each game has individual attributes that can be similar to those of other
games. However, there is no single, essential criteria shared by all games. For
instance, rules are imprecise in language games and children’s games. On the
other hand, most ball games and card games can be won according to clearly
defined rules. Not every game needs to have rules, be entertaining or declare a
winner and a loser.
Games can be clustered into groups, depending on similarities between them.
It is possible to distinguish ball games, children’s games, card games, social
games, language games and computer games. However, none of these genres
has strict taxonomical borders. There is a “family resemblance” between them
(Wittgenstein, 1953). Each member of a family is unique and illustrates the
rich diversity of its genre (Flatscher, 2002).
Adhering to Wittgenstein’s proposition that the definition of games in general
is at best fluid and vague, the following attempt at a definition does not claim
to precisely distinguish games from other entertainment applications or pasttimes. The definition given shall, however, suffice in narrowing down the
range of applications this thesis is intended for. To further illustrate the term,
examples of games are given throughout the following chapters, particularly
computer games and AR applications. Additionally, many game design principles can be employed to design all sorts of applications, and are not limited
solely to games.
A game can be described as a playful way of interacting with people or objects
with the aim of achieving a goal. “Playful”, in a definition of Huizinga (1955),
refers to a voluntary and absorbing interaction done for its own sake. Playing
is never necessary, but a willing choice to do something that is not relevant to
ordinary life. “Goal” can be defined in a very general sense of the word. It
may, for instance, be a player’s goal to experience the outcome of a story, to
determine a winner in a playful contest or simply to pass the time and enjoy
himself. What creates a goal is the willingness of the player to put effort into
reaching it (Costikyan, 1994).
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Appreciating Games
The term “game” may refer to many expressions of human playfulness, including idle play and creative expression. In general, games are defined as selfsufficient systems that have start and end points in between which the player
can change the game’s fantasy world according to a set of rules. For the use of
the term game in this thesis, however, some of the qualities usually listed in
the definitions of games need to be examined in more detail.
2.1.2.1. Self-Sufficiency and Interdependency
A game offers a fantasy world that is a closed system containing all relevant
information and rules. It is only so far related to the real world as is required
to support the player’s fantasy (Crawford, 1982). Inappropriate references
from within the game to the outside world may even ruin the player’s illusion
of being inside a completely coherent world. For example, a detective adventure set in America’s 1950s, should not confront the player with a safe, the
combination to which is “Michael Jackson’s birthday”. The fantasy world of a
game needs to remain self-sufficient.
Also, a game is usually defined as having no implicit relevance to the world
outside of the game. Caillois (1961), for instance, defines a game as selfsufficient in as much as it has no direct effect on unrelated games, work,
hardware, or humans who are not participating as players. This definition
must be reconsidered in the face of the latest development of game technology. Many games indirectly influence the outside world. They can, for example, influence work and sleep schedules, especially when a player is hooked to
a game or is afraid to miss a crucial opportunity for a bargain or victory while
he is off-line. A game might even influence the player’s finances, as is the case
with professional gamers who make money by farming online games and
selling their virtual profits to other players for real money, e.g. on eBay. The
act of playing has become a job for professional gamers, with the goal of
earning money and that goal is clearly outside of the game world.
If self-sufficiency is a quality of a game, some games of today clearly defy
their definition. Games, and this is especially true for augmented reality, can
be designed to rely on input from the outside world to function fully. Real objects and players can be tracked to act as input devices to a game. Even spectators, who are not participating directly as players, can be tracked and used
to influence the game. Without this input from the real world, augmented
games would remain incomplete, predictable and boring. The main quality of
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Appreciating Games
augmented reality games is no longer self-sufficiency but the interdependency
between the game world and the outside world.
2.1.2.2. Goals
The story of a game is designed around a set of minor and major goals. These
goals can be attained by adhering to the particular rules set by the game. The
player progresses through the story and, by accomplishing minor goals, finally attains the main objective. The attainment of the major goal usually signals the end of the game.
The degree to which the goals of a game are revealed to the player differs from
game to game. In racing games, athletic games and strategy games, the goals
are obvious to the player and are kept rather simple. Another prime example
would be Poker, in which the main goal is to win real money.
In simulations and story-driven games, such as adventures and role-playing
games, the objectives are only gradually revealed. Many classical computer
adventures such as Startrail slowly reveal their objectives (Figure 2.6). The
player starts in unfamiliar surroundings and adventures through a fantasy
world, exploring and learning along the way. With each encounter, new goals
may arise that lead the player in another direction.
Not knowing the final objectives can even be the fun of the game. This is most
obvious in the off-screen game Scavenger Hunt. The goal is to uncover all predetermined clues bit by bit, until the final piece of the puzzle is solved. Looking for the next objective constitutes the entire content of the game.
Many games start off by placing the player in a dangerous situation and indicating to him that his goal is to survive, as Costikyan (1994) points out. A
common starting point is to take the protagonist out of his familiar surroundings and confront him with a situation similar to: “You are lost and alone, surrounded by [insert evil creatures here]”. Games that started off their story this
way include Flashback, The Black Cauldron, Half Life, Quake, Oni, Heavy Metal,
Neverwinter Nights and countless others (Figure 2.7).
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Appreciating Games
Figure 2.6: Adventure games such as Realms of Arkania: Startrail
gradually reveal new goals throughout the game.
These games take the virtual protagonist from his comfortable, nice and
homely surroundings and throw him into intense danger, daring the player to
help him out. This initial clash helps to start a relationship between the player
and his protagonist. Afterwards, he can go on to explore the reasons for this
first threat and explore the intricate and complex story of the game, ultimately
finding the source of evil (Campbell, 1972).
Figure 2.7: Many games start off with a situation that puts the virtual protagonist in mortal danger, daring the player to help him out. Burntime takes place in
a post-apocalyptic setting where the fight for survival is exceptionally tough.
13
Appreciating Games
Modern development, however, especially in online games, shows a tendency
to more life-like human enterprises which do not end after a major victory.
The player has to set new goals for himself after he has finished one storyline.
Examples for this kind of never-ending adventures are Everquest, Guild Wars
and World of Warcraft. These games have a main story that can be completed,
with side-quests to add interest and length. Additionally, players can set their
own goals, be it to gain experience and collect items or to team up with other
players to vent their aggressions by raiding opponents.
Interactive installations, on the other hand, do not set any goals at all, and in
this respect installations can be distinguished from games. Installations do not
have a proper starting point and they do not aim at achieving an objective.
Even if installations offer clearly defined rules, they have no ending and offer
no point of victory to the player. Additionally, the intention of installations
usually differs from that of games. They try to foster creative expression in a
playful manner but they do not attempt to channel the user’s creative efforts
into achieving a specified goal. For a more detailed description of installations,
see Chapter 3, Section 1.4 “Interactive Art”.
2.1.2.3. Rules
Rules are the player’s means of achieving a goal. He can choose any action
that corresponds to the rules. They are given meaning only by their relation to
attaining a goal (Wittgenstein, 1953). Rules without an apparent correlation to
a goal might be seen as unnecessary restrictions. The player will understand
rules that are either personal values, a role’s responsibilities or a conclusive part of
the game.
The personality of the player defines what he is willing to do in a game. Moral
values can influence his decisions as well as the desire for respect and admiration from other players. In the game Fable, the player individually decides if
he is willing to kill innocent people to advance his goals or if he follows a path
of righteousness and protects the weak. Both options lead to a similar outcome
in the game and essentially the choice only depends on the player’s desire to
be good or evil.
A role’s responsibilities are similar to personal values in the way that they
arise from moral values. When the player controls a noble, dragon-slaying
knight in a fantasy game, his character will have different options to choose
14
Appreciating Games
from than a sly, drunkard investigator in a science-fiction detective game. The
virtual character has certain psychological attributes that limit his ability to
make decisions in the game. As a result, these limitations restrain the actions
that the player can take to achieve his goals. He can also take on roles in offscreen games. In the board game Heimlich & Co., he plays a private eye who
has to hide his identity. In volleyball and other physical games, the player can
take up defensive or offensive positions and accept the corresponding responsibilities within the team.
Rules that are an inherent part of the game are commonly referred to as rules.
They define how far a figure can move per turn in a board game, whose turn it
is to roll the dice next, what the figures in Chess do (Figure 2.8), how long it
takes to build a house in a strategy game, how much damage a sword inflicts
in an action-adventure, how much it costs to buy flowers for a girlfriend and
so forth.
Figure 2.8: Rules define the options that the player can choose from to attain
goals. Chess assigns each figure different abilities to make the game dynamic.
Rules formalize the setting of a game into comprehensible, computable and
logical parts. Good rules make it clear to the player what he can and cannot
do, by using intuitive, understandable and fair conclusions that can be de-
15
Appreciating Games
duced from the fantasy setting of the game. For instance, in a strategy game in
which units can learn different professions like engineer, scientist and worker,
it makes sense that research of new technologies requires scientists. Furthermore, the research can be sped up with a greater number of scientists. The
exact time it takes to do research on a particular technology depends on the
complexity of the technology, its importance to the course of the game, and the
available resources granted to the player. In this way, rules balance a game
and keep it within fair and reasonable limits for all participating players.
Rules are a frame shared by all players of a game to interact in an equal and
fair environment. According to Klages (1999), players abide to rules, while
being fully aware that they are doing so only to take part in the game. Schiller
(1795) even describes this combination of being aware of the rules and yet
loosing oneself in the game, as an educative quality, because it combines the
need for personal freedom with voluntary restraint.
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Appreciating Games
2.2. What is Game Design?
2.2.1. The Science of Game Design
The aim of a game is to offer enjoyment and entertainment to the player. A
state of continuous enjoyment is often referred to as flow, suspense or immersion. It is a state of complete balance between challenge and emotional reward, without excess frustration on the one hand or boredom on the other, in
which the player can explore the fantasy world of a game and, for a certain
time span, even forget his real world anxieties and worries (Overmars, 2005).
The science of game design addresses numerous influences that shape the way
players experience the world and story of a game. Consequently, game design
encompasses a wide range of subjects, e.g. psychology, pedagogy, social science, arts and even philosophy. The science of game design also features software engineering issues, issues of human-computer interaction, computer
graphics and artificial intelligence, as well as issues of hardware and interface
engineering (Overmars, 2005).
Due to the many influences on game design, the process of developing a
player-oriented game is full of variety, challenging and subject to constant
change and adaptation. The game designer has to be similarly flexible and
resourceful. Rollings’ book “Anatomy of a Game Designer” (2003) describes
the ideal game designer as imaginative, technically and mathematically competent, showing aesthetic awareness paired with drawing skills, able to communicate and to compromise. The task of every game designer is to shape the
story of his game into a unique experience for the player. To accomplish this,
he would have to be an excellent technician, a creative artist, a pedagogue and
a psychologist as well.
The versatile nature of game design makes it impossible for one person alone
to create an enjoyable game. Game design is a holistic process to which every
member of the development team has to contribute. It takes all sorts of abilities and know-how and permeates every part of game development.
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2.2.2. Playability
Playability could be defined as the amount of satisfaction a player gets out of
interacting with a game. It is the underlying and most essential criteria of
quality for a game. Playability describes the experience that players have and
thus the way they feel about the game. It includes parameters that are hard to
define like fun, challenge, satisfaction, enjoyment, achievement and motivation that the player feels.
Game design is the art of shaping innovative ideas on many levels and structuring them into a bigger picture which fully supports the player’s experience.
Whenever a decision has to be made concerning the introduction of a new
feature into a game, the first and foremost criteria should be whether or not it
enhances playability.
Playability can be seen as a sort of social relationship between the player and a
game. People want to be understood and accepted for who they are. When
communicating with another person, a prime human desire is to be accepted
and to have one’s efforts appreciated. Furthermore, these efforts should serve
a purpose and give meaning to the player’s enterprises. They should, for instance, contribute to making the environment better, safer, more beautiful or
more impressive. Most importantly, a person’s efforts should be rewarded, be
it by making the individual feel successful, satisfied, proud or content.
Players have similar desires and expectations when communicating with or
within a game. The game has to invite the player to stay connected. To accomplish this, it has to appear attentive and welcoming to the player, without being superficial or overly polite. Almost like good teachers or parents, games
should appreciate and support the player’s accomplishments, yet be critical
enough to ensure talent development—and they should never patronize.
Games have to take the differences in their players’ expectations into account
in order to be fair and meet the needs of the individual player.
Games can and should even offer a way of achieving goals that are meaningful to the player in his real world and with which the player can identify as a
real person. Like in the real world, what constitutes meaning and purpose to a
person depends on that person’s interpretation of the world. Purpose can be
attained by improving one’s skills (Tetris, TrackMania), by accompanying a
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character through the course of an unfolding story (Guild Wars, Neverwinter
Nights), by creating new worlds (Civilization, Populous), or by raising a unique
creature (Black & White, Creatures). Generally, the player should feel good
about what he is doing and enjoy himself, so he will want to spend more time
with the game that meets his individual desires.
2.2.3. Creating a Unique and Emotionally Appealing Game
The aim of game design is to create a unique, coherent and emotionally appealing experience for the player. This experience results from all aspects of a
game acting together to create a whole. Therefore the goal to create uniqueness, coherence and emotional appeal must guide all design decisions, from
game design to software engineering and hardware development. In this respect the creation of a great game relies on the choice of genre, theme, story,
atmosphere and duration. Furthermore, it relies on the design of virtual and
physical surroundings, of visual and audio content, as well as software features.
The theme and the story constitute the core and the overall framework of a
game. If all the features of a game correspond to the theme, the game will appear to be made from a single mould and the player will experience a convincing and coherent fantasy world. Sirlin (2000) gives an example:
If you want to make a game that creates the over-the-top, action-packed
experience of being a super hero, then everything else follows from this.
The game-play can’t be based on slow paced exploration. You’ve got to
get as much craziness on the screen as possible. The music has to be high
energy. The menus have to feel like super-hero menus, whatever that
means. Would Wolverine want to sit through a long cinematic sequence
at the beginning of the game? No way. Wolverine wants to rip though all
that crap and beat someone up as soon as possible, preferably within 5
seconds of turning the game on. (Sirlin, 2000)
The creation of an enjoyable game is a long and winding road which requires
critical thinking, reflection upon the game designer’s own experiences and
knowledge, reevaluation of achievements and the ability to change ideas for a
greater good.
Developing a unique experience for potential players requires one to understand their desires. Who should want to play the game? What do these people
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enjoy? What do they expect from a game? How familiar are they with computers? How much time do they want to spend with a game? How often do
they play? Do they like to play for ten minutes a day? Do they want to get totally addicted to a game and play non-stop for two weeks?
One way of evaluating the uniqueness and appeal of a game is to state its
theme in one sentence. What reaction does the statement invoke when telling
a friend or a stranger? Are there any unique propositions in it that differ from
existing themes? What will the player remember as especially entertaining?
Confronting the idea of a new game with questions like these can help to solve
several potential problems and discover necessary features. Considering as
many aspects as possible in the early stages of game design is invaluable. At
the beginning of the development process, changes that are made usually cost
comparatively little time and money. Refining an initial idea over and over
again is crucial in clearing up discrepancies.
Sometimes, it is easier to find problems when leaving the design process for a
couple of days. However, there is often not enough time to ponder an idea for
long. Instead, an idea can be improved when discussing it with members of
the target group. Important feedback can also come from colleagues or coresearchers, friends and non-gamers, grown-ups and kids. Especially people
who usually have views differing from those of the game designer can provide invaluable information. Some of the comments might be contradictory.
Including all the different perspectives into the planning stages can become
quite a challenge.
However, it is not necessary to incorporate all of the input from one’s interviewees into the design process. As stated above, only those features that are
relevant to the theme and the story should be included into the game design.
It is important to focus on a specific target group and to consider what features the game can offer to that particular group. A player will not gain the
most from a game that is made to be suitable for people from ages 3 to 90, because a game design will have to make a lot of compromises to accommodate
such a large and diverse group of players. In a case like this, the purpose of
the game might have to be reconsidered: Should many people be able to play
it, or should the game provide the most amount of fun and enjoyment possible
to a smaller target group?
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Analyzing existing products, their use of technology, or how they address
certain groups of players, can help to understand the benefits and draw-backs
of particular approaches and solutions. The way they use game design to employ rules and challenges, interfaces and technology for creating a pleasurable
experience can serve as a basis for understanding the current expectations of
players.
Existing applications serve as models of how to satisfy the desires of players.
These models can be computer games, but may also be found in other media
like board games, on mobile phones, even on radio shows and in movies.
Common ideas like puzzles, can be transported in a variety of different media.
Puzzle gamers who like Tetris or Memory will like the same game idea in an
AR environment, while Quake gamers might enjoy infra-red guns or throwing
balls too.
To make decisions about features or the technical setup of a game, it helps to
imagine the intended emotional experience of the finished game. When a
choice is made for a certain feature, it has to be developed for the game. All
features are commonly structured into a game design document (Lilleike,
2006). Features can be categorized into technical requirements and game design aspects of varying importance. Game design features require certain
technology to be implemented, therefore, it is recommendable to put the technical and game design features into a timeline that lists the order of prerequisites. Technical expertise is necessary to judge the time it takes to develop the
technologies necessary for the finished game.
Many features that enhance playability can be implemented with comparably
little technical effort, e.g. a flashing start button, a heads-up display for hints
and tutorials, an animation instead of a still image or a sound that gives immediate feedback to an action. Complex technical features are not always crucial to playability. For example, it might not be necessary to create a new
pathfinding AI or a speech-recognition agent who can engage in non-trivial
conversation with the player. The essentials of playability are in the details: an
interface with an intuitive and customizable layout, a way of giving the game
world a personal touch, challenges that are neither too hard nor too easy, atmospheric graphics and sound, etc. The fundamental technologies required
for most of these features can be implemented by programmers with little effort or even as a means of relaxing their brains.
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The more time-intense part is balancing these features. The aim of balancing is
to create a fair and delightful experience for the player from the available
features. Every option that the player has, every opponent that can stand in
his way, every twist and turn of the story has to be integrated into the rest of
the game. In general, features should be tested as early as possible to leave
time to adapt and balance them. Parameters and default settings can be
tweaked to adapt the amount of damage that a weapon does, the friction in a
racing game, the brightness of a button or the position of a map. Details can
make the difference between an unfair and unplayable game and a challenging and engaging one.
New games need not be totally different from existing ones, and this is true for
AR games as well. They can build on the know-how and conventions of existing games to offer the player the necessary amount of familiarity he needs.
Yet, they should lead on to unfamiliar grounds, offer new solutions to problems found in existing games, offer new interfaces to achieve a better quality
of interaction for the player, offer alternative displays and feedback devices to
convey a more intense atmosphere. The combination of popular gaming traditions with new approaches can create a unique, enjoyable and well-rounded
experience for the player.
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2.3. Influences on Playability in Game Design
The following chapter gives a brief outline of the complexity and importance
of game design. It introduces parameters that can be influenced and lists issues that need to be addressed in order to design playable and entertaining
games. More specific information on game design aspects which are unique to
augmented reality can be found in Chapter 3.
A game starts at a certain point for each player. From this starting point, a
story guides him through the course of the game. Throughout the story, there
are goals that the player can reach. However, no goal can be attained without
an effort. The game dares the player to fight for his goals by winning in challenges. Still, not all goals can be reached, because some might contradict each
other, like the noble king wanting both his sons to be heirs to the entire kingdom. Decisions have to be made according to the player’s personal values.
Each decision has an effect on the game world. In a game, decisions can only
be made in adherence to rules. Furthermore, for decisions to matter, the player
has to have a goal that he wants to reach.
2.3.1. Story
The story of a game defines the atmosphere that the whole game conveys to
the player. It sets the background of the game that contains all necessary details to bring the fantasy setting to life. It defines the history of the world, the
visual style of architecture and its inhabitants, the background musical score
and voices, the choice of a realistic or of an abstract comic world. In this way,
the story ensures that all relevant information is presented within the game.
What constitutes relevant information that needs to be introduced in a particular game does not only depend on the kind of story. It is also defined by
the player’s prior knowledge of the real world. For example, in a racing game,
the player has a large amount of knowledge from experience in the real world
and from playing other racing games: The car moves forward, it is influenced
by gravity, it can crash, be steered left and right, etc. When a game is labeled a
“racing game”, then players will automatically expect fast cars, intuitive controls and high octane.
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Appreciating Games
The story also defines the player’s role in the game, either as a participant in a
battle like in Quake, as a God-like entity, for instance in Populous, etc. The role
defines the perspective from which the game world is seen. Depending on the
role of the player, a racing game can either be viewed from inside a car, or
from a bird’s eye view, or from a chase camera and so on.
A story in the classical sense refers to a continuing plot with twists and turns.
Campbell (1972) mentions the “hero’s journey” as the fundamental structure
of every story. This structure of suspense and character development describes
starting points, challenges, and the growth of the player as he overcomes these
challenges and finally achieves victory or experiences a revelation. The hero’s
journey can be found in a game’s overall story, or spanning over several missions, but also within single maps and rounds. The stories on a smaller scale,
e.g. within each mission, contribute, in various degrees, to the main story
frame. They enhance the pace, maintain suspense and lead the player through
the story step-by-step. A game needs multiple levels of stories to communicate
depth, versatility and unpredictability.
In an adventure game, step-by-step achievements lead to the discovery of new
items and areas or they might cause a change in the story’s plot. Sometimes,
the plot even leads the player to a revisitation of a previously lush and fruitful
area that he is already familiar with and that is now scorched and lifeless, in
the face of new revelations in the story.
According to Costikyan (1994), strategy games often disregard the structure of
the hero’s journey. The player builds a base, defends it against occasional attacks and fights to expand his position. After the first half of the game, the
player either dominates his enemies or is economically ruined. Usually, the
ensuing clash of armies only serves to let the dominant player enjoy his victory, but it is no longer the intense and unpredictable climax of an epic strategical battle (Figure 2.9).
Side quests are constructed in a similar manner to the main story line. They
are independent stories and have no major relevance to the main plot. However, side quests can give depth to a story and bring new revelations to the
surface. They can contain in-depth information on characters, background stories and history or shed light on other parts of the main story. Additionally,
side quests let the player occupy himself with less relevant past times to gain
new items or a fresh perspective on the main plot. It is common to offer re-
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wards to the player for taking the time and effort to complete side quests.
These rewards can be bonus items, information, friends or areas that make the
challenges of the main story easier for the player. The value of the reward
should be weighed against the difficulty and duration of the corresponding
side quest.
Figure 2.9: Strategy games such as Starcraft often disregard the structure of the
hero’s journey. A game is often decided after the first half due to economical
reasons. After this, further developments often become predictable.
2.3.2. The Player’s Impact on the Game
The fantasy world of a game is designed to evolve in various degrees by influencing certain predefined parameters. These changes must be brought about
by the player’s own actions, either directly or indirectly. He must feel that his
achievements have changed the fantasy world, for the better or the worse, and
that his his decisions have an impact on the game. If the player of an adventure game slays a few evil minions, his actions will enrage a virtual antagonist,
who then destroys the player’s village. Even though the destruction of the
village is not within the player’s control, it was brought about by his own
actions and is thus coherently integrated into the evolving story.
Crawford (1982) suggests that the reason why interactivity has such a large
appeal is because interactivity reflects reality with all its intricate dependen-
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cies, its chains of cause and effect, its seemingly random events triggered by
the actions of people, etc. A picture or movie cannot convey these intricacies as
lively and vividly as an interactive medium can. Every interactive application,
therefore, should make intensive use of this unique quality and convey richness and intricacy of plot and character development. Interactive installations
should not progress along preset courses of events but react to what the user is
doing, whether he is playing according to the rules, making horrible blunders,
or acting too passively.
However, there is a downside to interactivity. The more influence a player’s
decisions have on the evolution of the artificial world, the more complex and
difficult it is for the developers to keep the game balanced. In the computer
game Red Faction, for instance, the player is allowed to burrow through the
ground and even to use explosives. Radical activities like this can easily sidestep the intentions of level design. The player might destroy the fantasy world
of the game, which would be counterproductive. The game would come to a
premature end. To prevent this, Red Faction places indestructible metal devices
at the most inconvenient places. This is annoying, because it betrays the whole
idea of choice, freedom and efficacy that interactivity promises to the player.
To keep the balance between leading the story of the game along preconceived
lines and giving the player the freedom to design his own story is a crucial
task in game design.
The game designer has to find a balance between the player’s true freedom of
choice and the complexity and problems which that freedom causes in game
development. An adventure game, in which the player can choose not to go to
work but pick flowers instead, or in which he can tell lies, smash a window or
go on holiday whenever he likes, would be utterly complex. Possibly so much
so that no AI could handle the effects of all the possible decisions and no company could afford hiring all the people necessary to produce the content of the
game. Therefore, the freedom of the player has to be limited within reasonable
boundaries, while retaining the impression for the player of being able to
make valuable decisions in the game. In the game Façade, the player communicates with a married couple (Figure 2.10). As the evening progresses, the
couple starts to argue and might split up. The player interacts with them by
typing text that is interpreted by an AI. The responses of the couple depend on
the player’s input (Mateas, 2003). In any game, the player will be satisfied
when he feels that his actions shape his experience of the game, even if the
story progresses in a mostly predetermined way.
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Figure 2.10: A game has to give the player the impression of being able to determine the outcome of its story, while challenging him with uncontrollable
elements. In Façade, he has to speak with an arguing couple.
In the installation Fishies (Stuppacher, 2005), the player can leave the game and
come back at another time. For example, a player might have tried to propagate a certain breed of fishies, or he has tried to make red skin-color dominant.
When this player returns, he will want to see some results of his prior actions.
Depending on the time that has passed since his last visit, he might still see a
few red fishies of his favorite breed. If, however, he no longer recognizes any
changes he has made, he might feel disappointed, frustrated or even futile,
because his prior actions were not important enough to have had a lasting
effect. An appealing game has to try and maintain as many lasting changes as
possible, while balancing the immediate and intense effect triggered by new
input with the goal of maintaining an exciting, predetermined and goaloriented design.
Especially in games like Fishies whose game design is based on the player’s
influence on the outcome of the game, it is important to prevent the game
world from changing too rapidly in too short a time. The game design has to
regulate the changing stages of the fantasy world and to keep them within
certain boundaries. The player should be able to experience cause and effect
satisfactorily, but he should not be able to overthrow the overall plan. Restriction of the impact of a player’s input is necessary to maintain control over the
story and to avoid having to bluntly reset all the game’s parameters and erase
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all prior changes. An unwise decision that the player made several hours ago
should not keep him from progressing in the game at his current location.
To keep the impact of the player minimal, while giving him the feeling of being able to make the best possible decision at any time, the game can focus his
attention by offering a dramatic and captivating story. Furthermore, challenges can keep him focused on his goal, while limiting his perceived range of
actions. Finally, incentives can offer him the creative freedom to personalize
his gaming experience.
2.3.3. Challenges
A game has a starting point and offers one or several goals that the player can
try to attain in the course of the story. To achieve his chosen goal or goals, the
player will utilize the rules of the game to his best knowledge but he will also
use his own personal skills that he can bring into the game: skills at decision
making or at handling the interface, his concentration and his perception and
so on. The appeal of a game will partly rely on its ability to challenge the
player’s skills in a well-balanced way so as to keep the player interested without frustrating him.
Challenges are created by placing obstacles between the player and his goal.
However, as Adams (1998) points out, whichever challenges are introduced to
make a game more interesting, they must be part of the fantasy created within
the game. Dropping monsters onto the player’s track in an action-racing game
set on a mutant ridden planet would seem quite coherent. Dropping monsters
on a racetrack in a Formula 1 racing game to challenge the player would be
utterly illogical and outside of the game’s fantasy world.
2.3.3.1. Difficulty
In every challenge, there is a risk of losing, e.g. of losing status, happiness, or
time. On the other hand, the incentive of gain and victory spurs the player on,
e.g. revelations that are important to the story, reaching new levels, getting
maps or new characters, a sense of achievement, posting a personal high-score
on the internet, etc.
The balance between the risk of losing and the achievement of winning is reflected by the level of difficulty. It should ensure the most enjoyable experi-
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ence for as many players of different skills levels as possible. If the difficulty is
well-balanced, the player perceives a high risk of losing, but is still able to beat
the game most of the time. This ensures a feeling of high self-efficacy.
The level of difficulty should not be kept constant, but should add a certain
rhythm to the game. Sirlin (2000) suggests the difficulty level to follow a sine
wave. Challenges can be more difficult at times, when they are followed by a
relaxing and comparatively easy part. In comparison, the arch of suspense that
Campbell (1972) describes, can be employed to make a game gradually more
challenging. The rise in difficulty has to give the player time to learn and increase his skills. After the culmination of suspense, the level of difficulty can
decrease to allow the player to bask in his success and make use of the numerous things he has learned throughout the game.
When in doubt about how to balance difficulty, it is preferable to choose a setting that is easy rather than one that is too hard. Few players will complain
about games being easy, but many players will give up altogether when a
level or a puzzle is too hard for them. However, games that are too easy are in
danger of becoming boring sooner or later. To prevent this, the game designer
should employ incentives (see Section 3.6 “Incentives & Details”).
When using high difficulty levels, the retry time should be short. The racing
game TrackMania includes many ways of failing the course, making it a very
difficult game in regard to reflexes and skill. However, the laps are very short
and a race can be instantly restarted by pressing the Delete key right above the
arrows used for driving. This keeps frustration low and makes the sense of
achievement, after finally beating a race, even greater.
2.3.3.2. Long-Term Motivation through Unpredictability
Long-term motivation depends on the potential of a game to create new and
unexpected challenges. Challenges keep the player involved in the game and
motivate him to measure his skills against that of others.
• Early adventures were based on a rigid storyline with only a single, predesigned and predictable path.
• Randomization introduced a certain unpredictability, which could create puzzles with more than a single solution.
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• Scripted events were introduced which generated seemingly intelligent reactions to the player’s achievements. However, scripted events can become
predictable for a long-term player, which makes the game less compelling.
• The use of AI can generate different reactions to similar events, depending
on the player’s prior actions. However, AI is usually very limited to certain
tasks, such as seek-and-destroy in first-person games, e.g. Unreal and Quake.
In these cases, advanced players can predict the responses of the AI rather
accurately.
• Multi-player games allow players to engage co-players of varying skill levels,
without ever being able to predict each individual’s response. The somewhat volatile nature of human tactics poses the problem of keeping veteran
players from killing off new customers. In an open game environment, it is
hard to keep players of different skill from competing. A solution employed
in online games is to have separate ares like tutorials for rookies, quests for
intermediates and arenas for experts.
Augmented reality can incorporate all these methods of ensuring long-term
motivation and of creating an exciting experience. Storylines can serve as the
underlying structure. Randomness can create small details and minor changes.
Scripts can keep players on the right track. AI can challenge their reflexes,
while the co-players ensure unforeseeable events and shape the social experience.
Another factor in long-term motivation is the possibility to experience a game
through different perspectives or characters. Star Wars makes it possible to
play a good Jedi or enforce the dark side, World of Warcraft lets the player
choose in the conflict between humans versus orcs. Additionally, different professions can be selected, each with individual skills that can change the way
that the player experiences an otherwise unchanging game.
2.3.3.3. Diversity of Challenges
A game can challenge the players on many different levels. It can test their
attention, challenge their physical skills, let them ponder a logically challenging situation or question, have them opt for certain values and beliefs, etc. The
challenge of a game can focus on the player’s social skills, like communication
and cooperation, or his dexterity, agility, reaction and reflexes, his thinking
strategy, his tactics or his memory. A game can motivate its players to improve
their skills. It can teach them to communicate with each other, understand so-
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cial frames of reference, enhance their language skills, or improve tactical and
strategic thinking.
Intentions for the design of AR games can vary, just like in the design of any
physical game. For example, Poker and Golf can be viewed as games that serve
either no inherent purpose other than entertainment, or they can be used as a
means to socialize, or earn money. In computer-related games the most common reason for playing is to have fun and be entertained.
Games for quick entertainment focus on a single challenge. They are usually
short and easy to learn. These games often consist of repetitive tasks that have
to be done quickly, e.g. sorting blocks in Tetris. More complex games incorporate different kinds of challenges. They can contain puzzles and mazes, social
collaboration, as well as fast-paced action where the player has to do multiple
things simultaneously. Many games combine social aspects and entertainment
with skill training and sometimes they even include higher level learning.
2.3.3.3.1. Action and Reaction
Games based on action and reflexes like Quake, consist of a clearly defined
challenge that the player has to respond to. The player is not required to conjure up complex strategies or make large-scale decisions in order to defeat the
system. He is concentrated on reacting to very simple tasks and stimuli such
as seeking out and destroying opponents in Quake. Nevertheless, the player
can constantly challenge his own skills by learning to improve the routes he
takes and the tactics he uses. Examples of this kind of games include the realtime computer action-games Mario and Sonic, Counter-Strike and Unreal. Many
physical games like ball games and EyeToy, are also mostly based on action
and reaction.
2.3.3.3.2. Strategy and Exploration
Strategy games challenge the player to think and develop strategies. The
player is required to understand complex systems of cause and effect, to assess his current situation in order to find the best possible decision. Most strategy games have a time-limit which increases the challenge to the player. Strategic and explorative games include Battle Isle, Masters of Orion, Indiana Jones
as well as puzzles and card games. A genre in between action games and pure
strategy games are Z, Zelda, Warcraft, Lemmings and Tetris.
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2.3.3.4. Playfulness and Goal-Orientation
As stated before, the word “game” is used in very different contexts and has
many different meanings. There is a wide range of what constitutes a game.
“Are you game? Olympic Games, The hunter’s game, Don’t play games with
me! It’s just a game.” Sometimes the word refers to playfulness and lightheartedness. Other games adhere to strict rules and require critical thinking,
some can even be harsh and challenging competitions. This degree of playfulness has little influence on the theme of a game. It can concentrate more on
creative expression, making decisions or on action and reflexes. Any combination of playfulness and theme is possible like a painting contest (competitive
creative expression) or throwing a ball just for the fun of it (free reflex-based
play) (Figure 2.11).
Figure 2.11: A game can offer different degrees of playfulness, ranging from free
and goal-based play to harsh competition. The game can focus its theme on
creative expression, decision making or action and reflexes.
Games that deal with Creative Expression usually show a very high degree of
playfulness and a very low degree of challenge. There is usually no clearly
defined goal that ends the game. The user simply interacts with an interface to
explore his options for artistic expression, e.g. painting, making music or creating other emotional or symbolic content. This mode of playfulness is found
in many interactive installations. In the installation Fishies (Stuppacher, 2006),
a virtual aquarium is projected onto a wall and virtual fishies follow users
who pass in front of the wall. When a user stops there and waves, or moves
around, fishies gather to feed on his movement, thus getting bigger. The user
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can, for instance, decide to feed certain fishies while neglecting others, thus
creating an evolutionary reaction. He can nurture fishies to become fat and
big, spawn a horde of tiny fishies, create colorful diversity, or bring about the
rule of beastly-looking carnivores. Fishies creates an ambient, playful environment that does not require the users’ full attention. There are no predetermined goals and pathways. The user is free to explore and enjoy the results of
his often random interaction with the installation (Figure 2.12).
Figure 2.12: Fishies allows the player to experiment with a population of fishies
inside a virtual aquarium by moving around in front of a projection.
There are also computer games that do not have predetermined goals but are
focused on the player’s exploration of possibilities. The most popular example
is the “Sim” series, e.g. Sim Life, Sim City, The Sims, etc. Will Wright (Maxis,
1992, p. 4), the creator of Sim City, calls the program a toy, not a game. In Sim
City, the player creates a goal for himself, like building the tallest skyscrapers,
maintaining a city only by public transport or running it entirely on solar energy (Costikyan, 1994) (Figure 2.13). Complex simulations allow the player to
build a fantasy world to his own liking. Contemplative thinking, developing
strategies and Making Decisions are the main active ingredients of the game.
Essentially, decision-making games challenge the player to optimize problem
solving (Dreiseitl, 2005).
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Appreciating Games
Figure 2.13: Sim City does not present the player with predefined goals. He has
to develop his own story, challenges and goals during the course of the game.
The player’s decisions are influenced by the opportunities presented by the
game which can be of high or low complexity. High complexity can be found
in the “Sim” games. In contrast, card games such as Solitaire and reactionbased games like Tetris are of comparatively low complexity. Thus, decisions
are influenced by fewer parameters and are easier to make. On the other hand,
reaction-based games offer very little time to the player to make his decision,
as is the case in Tetris. This creates an additional challenge for the player. It is
crucial to weigh the complexity of decisions to the time available to the player.
The action-puzzle game Abe’s Oddysee is a cross-over between a puzzle and a
reaction-based game. It involves several puzzles that can only be beat by
sound logical reasoning, as well as fast Action and Reflexes to put the theory
into practice and beat the game (Figure 2.14).
Games that focus on action and reflexes are made up of intense challenges,
often involving physical contest and the competitive comparison to others.
Usually reactions are not complicated, but test the player’s reflexes instead.
Examples include most physical games such as Catch and multi-player
computer-action games like Quake. In contrast to decision-making games, the
player is not expected to make far-reaching strategic decisions.
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Appreciating Games
Figure 2.14: The action-puzzle game Abe’s Oddysee combines logical reasoning
with action and reflex elements.
2.3.4. The Meaning of Virtual Life
Games should foster individual creativity. The player is given the opportunity
to shape the fantasy world of the game he has engaged in, and he can achieve
something that he cannot usually do in his real life. A game serves to support
the player’s fantasy, it should not recruit him to act out predetermined scenarios.
Decisions are necessary in situations where the player cannot do everything
that he wants. In other words, they are necessary when it is impossible for the
player to reach all of his goals. He has to decide which goal is more important
to him: Sell a precious painting to earn money but risk a fight over it with his
lover? Steal food to have something to eat but risk being caught and imprisoned? Decisions are made for values. The player has to ask himself, what goal
is most important to him (Costikyan, 1994).
At every stage of a game, the player should perceive options that allow him to
shape the game to his wishes. Only then will it make sense to him to try and
make a decision that brings him closer to his goal. The player will choose from
the options that he perceives to be available to him, weigh the possible benefits against the risks of each option, and then decide his further course of action. This process is identical to the way in which we make meaningful decisions in life. Längle (1987) describes the process of making the best possible
decision, at any given moment, as the meaning of life. The same process allows the player to shape the fantasy world to his best intention and, as a result, feel satisfied with what he is doing. In this respect, games might be called
meaningful.
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Appreciating Games
Frankl (1979) distinguishes between three levels of human existence, each of
which has to be sufficiently satisfied, in order for us to make decisions on a
higher creative level (Maslow, 1943).
• On the physical level influences like hunger, cold, fatigue or noise can disturb
a human’s well-being. As long as desires like hunger or thirst are not satisfied, we are reluctant to make decisions on a higher level. Computer games
cannot influence this level. Augmented reality installations, however, can
influence the temperature, dim the background noise and maybe even offer
snacks (Ikeda, 2002).
• On the psychological level we need to receive attention, care, love and friendship. We need to feel safe and secure in order to go on to the next level of
human enterprise. Computer games should satisfy this level as well. The
feedback a game gives to its player can make him feel accepted or even appreciated. The social interaction the game offers can simulate friendship and
the feeling of togetherness. Games should always include this level and satisfy its players’ needs in this respect.
• Frankl (1977) includes a third level that has usually been neglected in the
history of psychology: the noethical level. When human beings feel satisfied
on the physical level, when they feel secure and content, they are encouraged to strive for higher values. Creativity and the willingness to reach for
higher goals sets in. Work and craftsmanship, art and music, technology and
science originate on the noethical level. It is rewarding for humans to work
and fulfill their dreams, to strive to achieve a goal or to shape the world according to their values.
The decisions that we make in a given situation depend on the level which our
mind is focused on at the moment and on the possibilities or values we perceive in this particular situation. The options that we choose will depend on
the values that we ascribe to these options. When a value is important to us,
we put all our efforts into supporting that value. Doing so gives meaning to
the decisions we make and gives us the feeling of being successful.
Frankl, who, besides Freud, Adler and Jung, has founded an influential school
of psychotherapy, describes three kinds of values that influence our decisions.
Interestingly, these values can also be found in games. They even seem to be
crucial for the success of a game.
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Appreciating Games
• Sensual values pertain to aesthetics, beauty, social life and love. Examples
include watching a sunset, enjoying a delicious meal, or a meaningful conversation with a close friend. In computer games, a sensual experience is
created mostly through visuals and audio. These stimuli remind the player
of sensual experiences he knows from the real world. Reminding him of a
freezing snowstorm or a beautiful sunset on a beach will add many of the
emotions and sensations he experienced in the real situation to the game
experience. Augmented reality even goes a step further. It can directly involve real world sensations, like vibration, electricity or other haptic feedback and combine these with artificial experiences. Thus AR is perfectly
suited to offer sensual values to its player (see Chapter 3, Section 2.2.4
“Feedback Dimensions”).
• Creative values shape the world around us. By creating art, technology, scientific discoveries, by raising a child, sustaining a family, by fulfilling a job we
make creative values become reality. In games, it is common to have big,
over-the-top creative values, like gaining wealth and power, raising a huge
army, unraveling the plot of a royal intrigue and so forth. Games allow us to
toy with possibilities that real life commonly does not offer. Alternatively,
we can try out possibilities that we would never choose as important or
morally acceptable in real life.
Small achievements, too, make life and games diverse and enjoyable. The
experience of creation can be very satisfying. Building a sand castle with a
child on the afore-mentioned beach is done for the mere pleasure of creating
something. It does not even matter if anyone else notices the ingenuity of the
creation. The value of a creative effort lies in the individual’s sense of
achievement. Of course, positive feedback can spur us on, but appreciation
by others should not be the only value of our efforts. In games, the richness
of the game and the pleasure to the player is also often hidden in the details,
like the possibility of equipping a virtual hero-avatar with a unique outfit,
leaving a personal insignia on a tree in a far-away wilderness, or assembling
a unique hovercraft (see Section 3.6 “Incentives & Details”).
• Philosophical values determine how we regard and judge the world around
us. We are free to think of things as stupid or without purpose, or we can
choose to regard them as things full of potential and possibilities that are
waiting to be fulfilled. Even though it is not really necessary to deal with
hopeless situations in games, because every player can choose to stop playing and continue life in the real world, games have to consider their players’
potential for philosophical values. How does the player deal with frustrations waiting for him in the course of the game? How can the game designer
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Appreciating Games
assure his players to show the right attitude towards mishaps and obstacles,
towards virtual death and injuries? Games do restrict the player’s options
and it can be seen as a fundamental attribute of a game, that the available
options are limited. The player cannot do anything he wants at anytime, but
is restricted by the pre-set goals he can achieve and by the rules he has to
adhere to. Like in real life, he can only make the best possible decisions,
given his current circumstances. So even when playing just a game, a player
is requested to show a philosophical, maybe sometimes even a stoical valuesystem to accept the limits and dangers a game confronts him with. It lies in
the duty of the game designer to assure that the player is offered enough
incentives to accept the limitations of the game.
2.3.4.1.
Environmental Factors in Game Design
Players come from different cultures, environments, and areas. They have
varying experience with games and computers. Their ages, interests and fantasy diverge. Different kinds of players have different interests at different
stages in life. For example, wealth and power are not desirable to everyone
playing Sim City. Some players might find satisfaction in creating a society
without starvation and disease (Adams, 1998).
In order for a game to appropriately reflect the diversity of its players’ goals,
interests, intentions, values and wishes, it has to offer a variety of options for
shaping the fantasy world or characters in order to address these needs. For
example, a role-playing adventure allows the player to explore a fantasy
world and its inhabitants, equip his hero with custom-made paraphernalia,
craft armor and weapons to make him more unique. All these actions serve to
express the player’s individuality (Figure 2.15).
In Peter Molyneux’ Black & White, the player raises a god-creature that is influenced by good and bad deeds. It changes its appearance and skills, depending on how the player fosters the light or dark side of his character (Figure 2.16).
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Appreciating Games
Figure 2.15: In games like Guild Wars, the player can give his hero a personal
touch by choosing gender, looks and hair-color and selecting from a broad
range of outfits and weapons.
Figure 2.16: In Black & White, a personal pet changes its looks and behavior
according to the player’s good and bad deeds.
The best possible action that the player will take not only depends on his
value-system but on the environment inside and outside of the game as well.
For example, in a bar, someone is playing a virtual card game on a touchscreen arcade. With every card he moves, he will try to get closer to the goal of
winning the game. Sometimes, he might have to decide to make moves that
reduce his score like putting a few cards on a side stack in Solitaire, in order to
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Appreciating Games
increase his chances of winning in the end. During his game, he will be distracted by the people in the bar and the noisy environment. Loud music,
smoke, the bartender asking for the next order, or friends inviting him to join
them at a game of Darts can interrupt him at any time. This will take some
attention from his game, influencing the way he plays. He might decide to
stop playing for a few minutes, to continue after the distraction has passed.
These eventualities have to be considered when designing the card game.
There will probably be no stressful time limit, the range of interaction will
simply be point-and-click and no intricate decisions will be necessary to advance in the game. Thus, the game respects personal and environmental factors that the player is bringing into the game. If the game cannot control the
player’s surroundings, interests, intelligence, etc., it has to limit the range of
interaction accordingly.
The downside to a reduction in the variety of interaction has already been
mentioned. It diminishes the player’s individual freedom. If the player can
only press a “yes” button or a “no” button to view branches of a predetermined story, his influence on the game’s fantasy is greatly reduced. His role is
narrowed from being a complex individual with a variety of wishes and desires, to being a pawn focused on a low-level stimulus-response interaction.
This limitation, however, can be a necessary feature, if games that only offer
simple choices are addressed to the right audience in the right environment. A
point-and-click game that consists solely of clicking on every red shape that
appears on the screen does not take a lot of time and reasoning skills. Simple,
reflex-based games can be great fun because they do not require a lot of active
thinking. The player can relax his mind, enjoying his aptitude at quick reaction. In this respect, simple games are similar to watching television. They are
slightly interactive, but do not require any higher level thinking or making
long-term choices.
In a computer game called Moorhuhn, birds fly through a 2D environment
horizontally. The player has to click on birds to shoot them down and gain
points. More points can be gained by shooting smaller birds that are harder to
hit (Figure 2.17). The challenge in Moorhuhn lies in optimizing the simple
point-and-click shooting of birds. Only if the player is totally inactive, he gains
no points; he may shoot badly and still gain some points as a reward; if he is
good, he gains more points. Through constantly increasing rewards, the player
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Appreciating Games
is conditioned to try again and again to further improve his skills, in a way
similar to Skinner’s experiments (1948).
Figure 2.17: The click-and-point game Moorhuhn reduces the complexity of its
rules to a minimum and rewards simple interaction.
There are always more birds than can possibly be shot down. Furthermore, the
game offers a random selection of birds each time, changing their flight patterns and sizes randomly. Thus, the player might be successful once but not
the next time. These two unpredictable factors prevent him from ever feeling
that he has truly beaten the game.
2.3.4.2.
Rewards
Totally reduced interaction like the repetitive clicking in Moorhuhn or playing
slot machines (Figure 2.18) can result in addiction. Repeated action that is intermittently granted simple rewards such as points, acts like any of Skinner’s
(1948) conditioning and training of rats and pigeons. The behavior becomes
habitual which can have a significant negative effect on the player. Addiction
not only affects the player’s state of mind in the long run (Klages, 1999). Repetitive and addictive activities can leave the user drained and miserable
when he finally tears himself loose from the game. If he is lucky, he will not
return.
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Appreciating Games
When creating AR interfaces, designers should be careful not to create another
generation of slot machines. Random-number games are dull, plain, unchanging, and unsophisticated. AR technology should offer new chances that
enrich the player’s gaming experience. The player should be encouraged to
appreciate his achievements and continually increase his self-regard. In most
games, there are always more levels to explore, more gadgets to discover. No
matter how good the player is, there is always a way to enhance his current
situation. Throughout a game, he is challenged to fight, improve, gain, explore, reach and accomplish (Figure 2.19).
Figure 2.18: Slot machines can foster addiction by offering simple and repetitive
interaction with the hope of gaining money. Before big winnings are made, the
player’s behavior has usually become habitual.
The idea of a game is to entertain and improve the player’s life. A game is
obliged to offer emotional rewards. When the player is successful and has attained an important goal, he should not only be rewarded, but be encouraged
to bask in his feeling of success and emotionally enjoy the fruit of his efforts.
Many action adventures such as World of Warcraft and Neverwinter Nights, reward the player with experience points, skills and items, like weapons and
armor. He can use these to improve his current inventory and gain advantages
in future quests and adventures. However, the moment of reward, the experience of success, the elation of victory only lasts for a single click. The moment
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Appreciating Games
is shortened by trivialities like first having to travel back and forth, just to
speak to whoever burdened the player with the quest in the first place. This
person then bequeaths some experience points onto the player. Usually, there
is no way of telling where these experience points originated from. The player
might have rescued an alluring princess from the legions of the damned, vanquished a dreaded demon, assassinated a respected nobleman or simply
slaughtered a horde of farm animals. The reward for these actions is usually a
handful of clean and sterile experience points.
Figure 2.19: In most games, the player is constantly challenged to his limits but
rewarded only for a short span of time. Quake uses colorful statistics at the end
of a round as a reward.
Currently, online action-adventures are starting to introduce a more versatile
mode of reward, where a player’s actions determine his standing with certain
factions. If a player helps faction A, he is respected by them, but looses face
with the opposing faction B. Gaining social esteem or fame within a group one
admires seems to be even more rewarding than being able to buy new items or
skills. The interdependence between a player’s decisions in the game and the
development of the character enables the player to individualize his hero
through his own actions which, in turn, increases the identification of the
player with his hero.
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2.3.5. Complex Computation and Simple Rules
A game has rules to control the interaction of players. Rules define the starting
point and the end, and the path that players can take between these two.
When a game starts, it usually resets specific default parameters like the location of player figurines in board games or an empty inventory in computer
adventure games, etc. This serves to define the exact state from which the
players can progress, in order to control the development of the round.
As the game progresses, the ways in which players can interact with the fantasy world of the game are defined by its rules. Players can influence parameters like the movement of a character, e.g. in board games, and first person
shooters, or the combination of certain objects and triggers, as is required in
adventure games and puzzles. The rules limit the amount of control that each
player has over the game. The player’s actions are interpretations of these
rules and limitations. Rules should be fair, yet challenging to every player. The
process of tuning the rules is called “balancing”.
A game ends when either the victory or loss conditions are fulfilled. A game is
lost when a player can no longer influence parameters to achieve victory,
which is the case when having reached the end of a time limit, after having
died or having gone bankrupt. Imagine a financial game where players have
to gain the most money in order to win. A player who has invested all his
money and is no longer able to buy anything, might have lost. However, perhaps a prior investment can still afford him new cash, allowing him to continue playing. This sounds trivial, but a game has to coherently manage all
parameters that can influence each other. Clearly defined loss conditions can
help to achieve this. A victory condition can be reached, for instance, by
crossing the finish line in a racing game, or by reaching the damsel in distress
after having slain the dragon in a classical adventure.
After a game is finished, the player has to be kept interested enough in the
game to play another round. While this is mostly determined by the overall
quality of a game and the promise of further challenges, it is also important to
lead the player on to the next round by simple interaction, like having to
merely press a single button.
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In general, rules should be simple, yet allow a vast number of possibilities for
the player. He should be able to create his own individual experience while
playing. Rules that are too rigid to allow creativity or too complicated to allow
the player to focus his talents, his attention or interests on the game can easily
become frustrating or boring. The Japanese game Go serves as a prime example of simple rules and complex possibilities. Two players compete on a
square board by placing stones of two colors, black or white. The intention is
to simulate tactical warfare between the black and white armies. Stones can be
placed anywhere on the board. They can form lines, circles or filled spaces.
The aim is to encircle an opponent’s group of stones or to break a defensive
line (Figure 2.20). There is only a handful of rules in Go, but their tactical diversity has been filling books for more than a hundred years.
Figure 2.20: The Japanese board game Go has simple rules that create a complex
game with virtually endless variety.
In computer games, rules can be tremendously more complex than in board
games. However, rules should still appear simple to the player. The argument
for simplicity does not insinuate unsophisticated rules. The game’s internal
computation should be well-balanced and can be very complex. Developing
rules can be a treat for mathematical minds. Balancing rules by testing and
playing the game can be a lot of fun, too. The player, however, should see only
what he really needs in order to play - in contrast to the developers. In a simple racing game, it should not be necessary to assemble and modify a car before being able to play. The player might want to tune some attributes of his
vehicle, like friction and acceleration, after familiarizing himself with the
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game. The game should offer suitable default parameters and keep most of
them internal. For example, the multitudinous parameters influencing an AI
opponent do not need to be visible to the player. He should only see a single
difficulty setting or, if possible, the AI can autonomously adapt during the
course of a game. AI games can, for example, become more challenging when
facing advanced players, or friction can increase on snowy racetracks, etc.
In order to balance the complexity of rules to their multiplicity, the number of
parameters that can be influenced by the player should be kept at a minimum,
while letting parameters cross-influence and overlap each other. Complexity
can be achieved through internally complex and sophisticated computation of
a game’s reaction to the player’s input. But, as has been said before, no matter
how complex internal computation might be, it should always appear intuitive and understandable to the player. When he cannot grasp the correlation
between his input and the game’s reaction, the game will seem unfair or stupid. Eventually, confused players will become frustrated and walk away.
To keep the player from getting frustrated, the learning curve should be kept
low, too. The player should progress easily from his very first encounter with
the game to learning and evolving along with the gradually unfolding story.
Particularly, a complex story with many rules must introduce rules step-bystep. In the first stage, no more than two or three rules should be necessary for
success. This will gratify the player right from the start and keep him interested in the game. If he continues playing, more detailed rules will be introduced, making the game more diverse and interesting. After the player understands the entire set of rules required in the game, he can still be led to discover advanced tips and tricks that help him become more efficient and successful. As he spends more time with the game, he will understand its inner
working and develop new tactics to utilize his knowledge.
2.3.6. Incentives & Details
Details give a game structure, texture and a feeling of intensity. They make the
game seem closer to reality by offering many, seemingly irrelevant, visuals
and possibilities. In World of Warcraft, the player controls a character who can
run around the world to explore, slay monsters, trade and so forth. This basic
setting is brought to life through details: different skins and clothing for each
race, landscapes with grass that moves, animals that populate the landscape, a
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market hall built from old wood that gives the impression of a lively bazaar
(Figure 2.21). All these details are irrelevant to the rules and challenges of the
game, but they are most important in transporting an experience of reality and
immediacy to the player. The game would be utterly lifeless and bleak if it
sported only a dreary, dead landscape with a repeating texture, a gray cement
market hall and no animals except for hostile beasts.
Figure 2.21: The World of Warcraft creates an emotional experience for the player
through its detailed, unpredictable and lively fantasy world.
Details that gradually reveal themselves act as incentives, unveiling depth and
complexity as the game progresses. Players can make new discoveries all the
time, gaining a sense of learning and achievement. Sirlin (2000) calls these
gradual rewards “small doses of fun”, that keep the player entertained and
feeling successful.
Incentives can be offered through new content, like visual sets, that change the
atmosphere (“The beach maps are really great, but the ice levels are always the
tough part to get through.”), or tactical instruments, like upgrades, extras and
new units. Online games sometimes present new content on holidays like
Halloween, Christmas or Easter (Figure 2.22).
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Figure 2.22: Online games such as Guild Wars occasionally present new content
as incentives on holidays such as Halloween.
Another important kind of incentives allow the player to express his individuality in an environmental context. Players want to give their surroundings a
personal touch, similar to real life where they decorate rooms, use customized
backgrounds on their computers and so forth. The player should be able to
leave a personal mark, even if it is only small things that do not change any
game parameters, e.g. painting his logo on certain objects, changing the look
of this character or car, uploading a photo, building a virtual house for others
to marvel at, or speaking his mind to other players (Figure 2.23). This allows
him to satisfy individual wishes and desires, which is essential to identify
with a game.
Figure 2.23: In FireArms, each player can spray-paint a custom-made logo
onto the virtual surrounding to give it a personal touch.
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2.3.7. Toys
A game is mainly based on human interaction, be it humans interacting with
each other, or humans interacting with devices. I shall refer to such devices,
that are intended solely for the use in a game, as toys. Toys can appear to be
inherently sentient, like computer consoles, or they can be intermediary, acting
as go-betweens for the player and the fantasy world of the game.
The most fundamental interaction is to use the human body. Games that utilize the capabilities of the body, ‘un-augmented’ with toys, can be played almost anywhere, at anytime, by anyone. No helping medium is required and
there are no unfamiliar devices that have to be handled. In addition, purely
physical games are often extremely challenging, invigorating and satisfying.
Examples include running to play Catch, playful wrestling, or Rock-PaperScissors.
Toys make it possible to achieve extraordinary feats, which would be hard if
only the human body were used. For example, baseball bats and tennis rackets
let players shoot balls in a way that would not be possible with bare hands.
Passive intermediary toys are used to enforce rules, like the wooden frame that
marks a goal, or lines of chalk that mark a tennis field, a table with a backprojection screen. Architecture and hardware design guide players through a
game, like a maze or race-course. In addition to passive toys, which create the
backdrop of a game, active intermediary toys serve as the actual input devices
for the player. These include balls, baseball bats, mouse and keyboard, buttons
and many more. Examples for games using a combination of passive and
active intermediaries are football, hopscotch, twister and most other physical
games. Active toys have to be available to every player, they should be robust,
light and safe.
Intermediary toys can be designed for a specific purpose, like bow and arrow
and baseball bats. These are optimally engineered for a single task and are
normally not reused for other purposes. Alternatively, intermediary toys can
be designed to be multifunctional, serving any purpose that the players come
up with, while they adhere to the rules of a specific game. For example, balls,
dice and cards, Lego bricks, mouse and keyboard, PDAs and others that serve
more than a singular purpose.
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Sentient toys can react to a player’s input and come up with changing, but not
entirely random responses to similar situations. This creates a more unpredictable and flexible environment for the player, resulting in the feeling that
another sentient entity is convening with the player. In computer games, artificial intelligence algorithms attempt to simulate another player. The AI player
has to act according to the rules of the game, just like a human player. This
restricts the AI to play fairly. On the other hand, it also has to challenge the
player. This would lead to very intricate AI in complex games. As a result, AI
players are sometimes designed to cheat. In strategy games, for example, it is
not uncommon for the AI player to gain money without resources, construct
buildings more quickly or get free reinforcements when in danger. AI players
who cheat too obviously will not challenge the player, but offend him, often
resulting in anger or counter-cheating by the player. To avoid this, the AI
should be kept simple and well-tested, cheating only where the player cannot
detect it.
Augmented reality can combine both physical interaction with the human
body, with intermediary toys, like tangible interfaces and display technologies, as well as sentient toys, which are well-known from computer games.
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3. Augmented Games
Chapter 3
Augmented Games
3.1. Augmented Reality
3.1.1. What is Augmented Reality?
“Augmented Reality“ (AR) is commonly defined as the enhancement of real,
physical surroundings with virtual information (Azuma, 1997). The classical
AR application uses a see-through head-mounted display that allows the user
to view his environment, overlaid with virtual 3D computer-graphics, displayed on his eye monitors (Figure 3.1).
Figure 3.1: The real world is overlaid with virtual information in augmented
reality. Real-time applications like Archeoguide or ARIS demonstrate 3D graphics
embedded in a real environment.
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The percentage of real and virtual elements within an AR application varies.
Milgram (1994) describes a continuum between the real, physical environment
and the purely virtual world of computers. This continuum spans from reality,
via the augmentation of reality with virtual elements, over the enhancement of
virtual worlds with real elements, to pure virtuality.
AR research has led to the development of so many applications of diverse
technology that it is difficult to clearly define the boundaries of augmented
reality. The combination of the real and the virtual seems to open up boundless possibilities. In this thesis, augmented reality refers quite generally to applications that utilize both virtual and physical elements. Games that make
use of this technology are no longer ‘just’ computer games or traditional
games. They can create a new gaming experience through the use of AR technology and are hence referred to as “Augmented Games“ (AG).
3.1.2. Game Design for Augmented Reality
In conventional computer games, the player’s attention is focused on the
screen rather than on the real world. This reduces the range of activity and
social collaboration. Intuitive interfaces free the players’ attention, allowing
them to concentrate on their fellow players and enjoy the experience together.
Alternate interfaces, such as cameras and microphones, also change the way
the player interacts with the game. Through the novel approaches of AR, the
player gets involved in the game both mentally and physically. He can use his
own body to manipulate objects. The virtual game can be extended by real
obstacles, by sound input from real environment or by constantly changing
custom-made interfaces. Revolutionary technical features ensure a playeroriented and enjoyable experience. The additional possibilities of AR can enhance playability enormously.
AR games can learn from both computer games and off-line games (Schmalstieg, 2005). Fundamentally, game design for augmented reality is the same as
for classical computer games. However, the methods currently available to
describe games are no longer complete for augmented games. Game design
for AR must encompass all the additional aspects, focusing on the question of
how to combine elements of classical computer games with the technology of
augmented reality to create an entertaining and satisfying experience for the
player.
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In addition to the game design aspects introduced in the previous chapter,
there are, therefore, many more options for the game designer of augmented
games. The following chapter discusses different aspects that are unique to AR
games. Amongst the numerous options, Szalavári (1998) mentions the ability
to display different information to each participant, to encourage social communication between players and to allow interaction with the game physically
and in real-time.
3.1.3. Development of Augmented Reality Applications
Augmented Reality applications are usually developed with the goal of creating a technical prototype. The intention is either to test new ideas, investigate possibilities or conduct technical studies. These prototypes lead to a better understanding of current technological possibilities and spur further research.
Many prototypes are intended to illustrate a novel idea or technology. They do
not need to be flawless products that could be sold at stores. Playability is
usually not an important factor in the development of prototypes, either. As a
result, many ingenious prototypes are presented in a way that keeps many
spectators from realizing the potential of the new technology or interaction
device. Getting attention and user feedback, however, is always beneficial to
the development of a prototype or theory. Games at conferences and innovation shows offer a good way of attracting audiences and transporting an idea
in a casual and non-committal way. At conferences people are in a sort of
learning mood and more willing to experiment with new interfaces or technology. Additionally, games that are introduced as prototypes can be designed
to focus solely on a certain aspect of a new technology. The feedback from
players, too, will be centered solely on this aspect (Starner, 2000) and will
therefore be more to the point.
Even if only intended as a prototype, a game should be fun, challenging and
entertaining, and it should not only fascinate the initiated by amazing technology. To quote Csikszentmihalyi (1977), “a game must engage all players on
an emotional level”, making the technology behind the setup seem irrelevant
to any player who is tied up in the game. This will result in a positive experience and leave players interested (Trappey, 2005).
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For creating player-oriented prototypes, it is crucial from the start to make the
player the center of the design. The game should think in the player’s terms.
The technology inside the game should be the interpretation of the player’s
wishes.
Consequently the game design process needs to focus the entire development
effort on the finished, enjoyable product even before the first lines of code are
written. Schmalstieg (2005) differentiates between the “how to implement”
phase that sometimes does not progress to the “what to show” phase. If game
design focuses mostly on featuring a new technological aspect, while leaving
the game design process for later, some technical features might have been
implemented unnecessarily, because in the process of game development it
becomes apparent that they are of no use to the mechanics of the final game.
On the other hand, many desirable game design elements may be restricted
due to technical reasons if the technological framework has already been implemented.
Whether a prototype is focused on the technology or on the finished product
and the player, its purpose is to convey an idea to the public. Consequently,
the main goal should be to refine a key aspect of the technology into a wellrounded game-prototype.
It is not necessary to make grand rearrangements in the development pipeline
of AR prototypes. Game design can enhance the established development
process to create richer and more satisfying game prototypes.
In the development of games, particularly in technical research, there is a
compromise to be made between what is technically feasible, what is economical and what the player might enjoy most. On the one hand, the technology needs to be robust and the software has to run without errors. A game has
to be thoroughly designed and refined into a well-balanced and enjoyable
experience. On the other hand, the amount of working hours, the number of
people working on the prototype and the funding are limited. Limiting
working hours, however, by designing simple games or focusing the game on
a single means of interaction reduces the complexity of the game, the intensity
of the experience and its emotional depth. It also reduces the impact on the
player and, maybe, the success of the game. Designing a prototype is a matter
of finding a balance.
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At present, most prototypes of AR games are not developed into commercial
products. In the mobile sector, companies have been supporting research, with
the result that several location-based games have become rather successful,
with communities supporting these games. Mobile applications run on existing hardware and are much cheaper to produce and to distribute than most
AR applications. For these, the money and time necessary for a prototype to
evolve into a finished product are usually not available.
3.1.4. Interactive Art
Interactive art installations are different from games, but they also employ AR
elements. Their use of augmented reality technology can also shed new light
on AR games.
Itsuo Sakane (1997) broadly defines interactive art as “simply art that involves
the participation of the viewer”. Weiß (2004) uses a similarly general, but more
technical definition and describes it as “an artistic activity that would be impossible and meaningless without the computer”.
Interactive art installations usually attempt to induce a user response like a
sensual experience, be it amazement, bewilderment or simply a short distraction. To achieve this, interactive installations are often focused on utilizing a
single means of interaction. Users concentrate solely on one interface made
available to them. For example, Small Fish by Masaki Fujihata employs a projection with abstract elements like lines, rectangles and bubbles. Each element
influences musical elements, similar to musical notation where written notes
define the sound of music. Users can shift and change the abstract elements to
experiment with the resulting composition. In this way, users are engaged to
analyze how abstract elements and music correspond. They can do this by either playing leisurely with the installation or attempting to understand the
underlying structure of the synthesis of abstract elements with the music (Fujihata, 1999).
The famous Videoplace (Krueger, 1974) lets users interact by using their silhouettes. The application switches between several modes of interaction whenever a new user enters. The image of the user can be translated, scaled and
rotated. One user can scale the outline of another or let it balance on his finger
(Figure 3.2).
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Figure 3.2: Videoplace places the user’s silhouettes in a virtual playground.
In Camille Utterback’s Text Rain (1999), the user moves in front of a wallprojection, where letters fall down and collide with his shadow. The position
of the user is tracked and aligned with the virtual world so that the virtual
letters and the user’s shadow interact (Figure 3.3).
Figure 3.3: In Text Rain, letters drop and collide with the user’s shadow.
In the installation Butterfly Garden, the user can cause new butterflies to appear, by holding his hands above an arrangement of flowers. The virtual butterflies are projected onto the user’s palms and onto the flowers. They fly
around as autonomous entities until they disappear between the blossoms
(Montandon, 2006) (Figure 3.4).
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Figure 3.4: In Butterfly Garden, the user can spawn butterflies
in the palm of his hands.
By concentrating on a single method of interaction, interactive art offers a sort
of laboratory environment to experiment with new interfaces. A single kind of
interface technology can be analyzed for user feedback (Nielsen, 2003). This
can aid game designers to analyze the experiences created by the installation,
in order to understand exactly why its elements form that particular kind of
experience (Sirlin, 2000). Attributes such as common ways of interaction and
user responses on a tactile or emotional level can be derived for each kind of
interface. These attributes can be useful for the controlled design of a user
experience. This is required in games, where different interfaces can be employed to create a certain experience.
For example, the designer of an AR racing game might choose between controlling cars with gamepads that allow users to accelerate and steer, and a
gesture-based control where cars always go to the spot where the player
points with his index finger. Each control offers a different experience to the
player. The first approach conveys a more direct feeling of speed and control,
whereas the second alternative involves the player more as a commander than
as a driver. The game designer has to decide which interface is most suitable
for the experience that the racing game should convey.
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Understanding the effects of new tangible interfaces and other interactive
technologies is the basis of employing them knowingly in a game (Barrett,
2000). Every interface influences how the user regards the installation and his
own options to influence it. A simple, cheery and colorful interface differs
from a complex, technical and sterile interface in the effect it has on the user
both mentally and physically. Several interactive-art installations already
make excellent use of different interfaces to create an intense illusion for its
participants and to produce a free and creative environment for the user. Not
many of these installations, however, attempt to create an immersive gaming
experience.
An enjoyable augmented reality game needs to present a robust and yet innovative technical interface, while being as engaging as a traditional computer
game. By combining the approach of interactive art, to experiment with a single interface and analyze feedback, with the research aspects of developing
new AR applications, it is possible to create well-tested and innovative games.
It is one of the challenging aspects of designing new AR games.
3.1.5. Conceptualizing a Game: Buffet Battle
Every initial idea, be it for a computer game or an AR game, faces endless revisions and corrections, constantly adapting to new problems and challenges.
However, in AR the designer does not only have to consider all the usual
problems of classical games. He has to take the physical and the social dimension of the player’s real world into account as well.
The following example is intended to illustrate the numerous considerations
that can influence an AR game concept. Imagine a projection-based strategy
game in which players control opposing armies, called Buffet Battle. The armies are seen from a top-view and the player controls them with his fingers by
selecting groups of soldiers and pointing to targets. In this case, the game is a
classical on-screen application, with the only difference that instead of a
mouse pointer, the player interacts with his fingers. Because the interaction
only involves two-dimensional information, very similar to the way a mouse
is used, there is no need for augmentation; there is no reason within the game
design for a complicated setup and interface.
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However, the player can move his fingers in three dimensions, not only two. A
planar game limits the physical possibilities of his hands. If a game were to
incorporate the natural movement of fingers in a three-dimensional space,
augmentation could be valid. A 3D AR-game would be more suited for fingerbased navigation.
It is still possible to restrain the interaction to a flat surface. Magnets, for instance, that stick to the game plane could be used for a two dimensional version of Buffet Battle. A magnet’s position could correspond to the position of a
cohort. However, the speed at which magnets can be pushed around by the
player would make the game based on fast action and reflexes. In order to
maintain realism of the movement speed of the soldiers in the virtual game,
they would need to be designed not to exceed a certain maximum speed.
A way past such logical inconsistencies is to use the magnets as a target location for a cohort. The movement of the cohort itself is controlled by an AI
agent. The player shapes the battlefield by placing the magnets or other real
obstacles on the game plane, thus influencing the routes of his troops.
At this step of the game design, another problem becomes apparent. By restricting the influence of the player on the progress of the game, his experience
of being in control of the battle also diminishes. As soon as an outside influence, like the AI in this case, appears to influence the outcome of the battle,
players who are on the losing side will blame the system or the controls for
their demise. As was stated before, the player should never feel cheated by a
game. The need to be accepted and appreciated has to be considered first and
foremost by the game designer.
A possible solution would be to keep the individual AI agents to run the
members of the opposing armies, but to change the role of the players from
commanders to spectators. The players could watch the unfolding events on
the battlefield like the ancient Romans did in the amphitheater.
For a game, however, simply watching the action from above would be boring. Spectators like to have some control over events, even if this control is
restricted to exploring and understanding the events of the game and cheering
or booing to them. Why not put the action inside the world of the spectators,
so they can explore the events on the battlefield? Imagine high-tech faeries
battling grim ogres on the buffet tables at a conference or business meeting.
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The virtual soldiers would remain invisible to the human eye until the spectators use magic monocles, e.g. hand-held shutter-glasses, to inspect their surroundings. Then, between white ceramic dishes, for instance, and a pile of
oranges, the spectators would behold a group of three ogres working their
way to a faerie hideout. A spectator could take sides against the ogres and interfere by moving the oranges to block the ogres’ track or even to crush a few
of them. Thus, the spectator could interact with the game, change the fantasy
world of the game and become a fully appreciated player again.
The idea of the game described above shows only a few possible ways of reasoning in game design. Considering the multitude of influences on the experience of the player is of vital importance. It helps to present innovative technology in a player-friendly way and meet the needs of modern consumers and
product managers. Augmented games can make use of the enhancements that
new technology offers, but they should go beyond building purely technical
prototypes to illustrate a new interaction device, tracking algorithm, headmounted display or 3D shape-extraction setup. New technology should be
employed to enhance playability and offer new and improved gaming experiences. In the long run, augmented games might develop into a rich and versatile market with quality products that appeal to the general public and take
the experiences of computer games further, enriching them with emotions and
interfaces that today’s players and non-players have not yet dreamed of. In
the near future, AR games could help to saturate public casual-gamer markets,
while supporting the trend of technological innovation of recent years.
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3.2. Design Aspects
3.2.1. Space
The design of the space of a game is one of the most interesting ways to shape
augmented games. In regular computer games, virtual worlds take place in an
entirely simulated environment of time and space. All aspects of the game are
controlled: visuals, sound, time and movement of the virtual player (Ruedenberg, 1995). This makes it easy for a game to convincingly convey a fantasy. In
contrast, AR games always face comparison with the real world. The player
can move around in his real-life environment and time seems to pass as it
ought to. This has an effect on both the virtual and the physical part of an AR
game: Virtual shadows of objects have to seem as real as that of their physical
counterparts (Supan, 2006).
Furthermore, if the player can move freely in the physical world, movement
within the game cannot be affected by a collision-detection or messages like
“You cannot go there!”. Every restraint in movement has to be logically deducible from the game and must be comprehensible to the player.
Space controls movement and attention in an utterly immediate manner. It
supports the emotional experience, shapes the actions and movement of the player
and can convey a game’s rules in a graspable and intuitive way.
An emotional experience is conveyed by the design of space within the game.
Dark and brooding settings induce uncertainty and fear; futuristic and technical surroundings may seem sterile and austere; while lush greenery and nature with wooden and earthen tones inspires warmth, security and serenity.
Clearly visible technological gadgets such as cameras, projectors, cables, sensors, blinking computer-stations and trusses convey an experience of an
amazingly advanced and chaotic research lab that ought to have people with
white coats scurrying around. Space is one of the major factors in bringing the
experience of a game to life. This is applied at set design and matte painting in
movies (Figure 3.5), at stage lighting in theaters and at level design in computer games (Adams, 2002) (Figure 3.6).
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Figure 3.5: The architecture of space conveys an emotional experience. This has
been applied in theatre and film since early movies like Nosferatu.
In these cases, the viewpoint is controlled by either the camera in a movie, the
seats in the auditorium of a theatre or the player’s character in a computer
game. Similarly, the virtual content of an AR game can be controlled by the
virtual camera. However, in the physical world, players can look and move
around freely - unless the game setup controls the player’s movement. This control can be achieved in several ways, illustrated by the following examples
taken from the real world: In a hospital, directions are given by color-coded
lines on the floor, for patients who are unfamiliar with the environment. In
front of a cinema, a waiting-line directs people to queue in a zigzag line. In a
maze, directions are limited by walls, corridors and junctions. In a computer
racing game, the course is defined by the color and shape of the road, its border, and other elements such as ramps and loopings. In an AR tabletop game,
players can be invited to take their places at a four-sided table with four control devices.
Figure 3.6: Computer games also employ the design of space to express setting,
emotion and foreboding. Extreme architecture like that sound in The Day of the
Tentacle, can be achieved more easily in the virtual world.
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Space is defined through the design of architecture and other physical elements, as illustrated above. Space can also be established through the relationship of moving game elements like players and obstacles. In the AR game
Human Pacman (Cheok, 2004), players chase each other almost like in a game
of Catch. One player is the “king of the hill” who has to be captured. In Human
Pacman, the spatial relationship between the players defines the current state
of the game, whereas the position in absolute space is irrelevant (Figure 3.7).
Figure 3.7: In Human Pacman, space is defined mostly through the position of
the players relative to each other. The player (right) runs around the real world
(left), avoiding capture by human ghosts. To escape, he is guided by another
person (top right).
The architecture of a game space also determines and supports rules, like a
goal in soccer does, or chalk lines in Hop-Scotch. The design of the space
should make use of existing conventions like paths, door-handles, arrows or
buttons, in order to convey the rules and restrictions of the game as clearly
and directly as possible (Andrews, 2005). A physical game called Quasar uses a
hall which is separated in two halves for two opposing parties and which
contains obstacles to be used as cover. Players wear low-intensity laser rifles
attached to plastic armor with light sensors. The hall, with its obstacles and
predefined pathways, conveys a feeling of restricted movement. It implies a
competition between the two team’s areas. Additionally, the obstacles serve as
a tactical playground, containing visual cover and obstacles to focus the attention of the players.
The player can only encompass information that is made available by the
space that is provided by the game designer. Consequently, the game designer
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can manipulate the information and attention of the player by space (Adams,
2002). Most of the player’s perception is defined by space. By controlling the
player’s perception, his basis for decision-making is limited. He cannot make
a global tactical decision, because only a part of the game is visible to him.
When designing a game, it is necessary for the game designer to step through
every position in space, imagining the player’s most likely decision. This way,
probable routes that lead through the game can be analyzed and adapted to
support the story and goals of the game.
3.2.1.1. The Dimensions of a Game World
The dimensions of a game are very versatile. They can be spatial, temporal,
emotional or social. The game can lead the player on a spatial trail like a racetrack, a storyline or along a musical composition.
3.2.1.1.1. The Physical Dimension
The Area of an AR Game is freely variable in size. A game can take place indoors or outdoors. Participants can move within a room, a hallway, in front of
a screen or they can play outdoors, on a football field or even use a city as
their playground in a GPRS game such as The Journey (Jakl, 2004).
Imagine, for example, a stealth-op tactical game in which players take on the
roles of seekers and runners, with the aim of locating a target, or avoiding
capture, similar to Cops and Robbers. Seekers attempt to capture runners by
coming within their perimeter. Runners can win by avoiding capture until the
end of a time limit. The game could be played on individual computer screens
in the same room, with each player steering an avatar like in a first-person
shooter. In an alternate real-world setup, the players could move around in a
large, futuristic room, looking for each other. The room is furnished with a
cushioned interior that forms tracks, hideouts and covers. Each player is
equipped with a one-eye see-through head-mounted display (Microvision,
2006) to display game information and group members. When a seeker comes
near a runner, he scores a point. On an even larger scale, the game could take
place in an open environment, with players moving around in the open. Each
player is equipped with a GPRS device that displays the positions of other
participants. Once a hunter is within a certain minimum range to a runner, he
has automatically captured him and thus increases his own score.
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The area of a game has to fit the experience and fantasy setting of the game.
The area that can be used depends on which technologies can be employed
and financed.
The Area of Interaction describes the space that the player can directly influence with his decisions. The player’s decisions have an impact on the game,
but he can only bring about changes in a part of the game area. Usually, the
player will only influence his immediate surroundings, causing changes that
he can see. He has to be able to understand the correlation between his actions
and the effect on the game world (see Section 2.2.4 “Feedback”).
The player can influence his surroundings through the use of smaller or larger
devices. He can play on handhelds such as PDAs or mobiles, touch a computer screen, move around large, fluffy objects, influence a wall-sized projection or a room-filling electronic setup.
The Movement of the Player, on the other hand, is limited by the area of the
game. The amount of physical participation of the player depends mostly on
the challenges and goals of the game. He can be required to walk slowly, run
around incessantly, remain in the same place, or even perform kung fu moves
and aerial stunts (Hämäläinen, 2004) (Figure 3.8).
Figure 3.8: Intense movement is required in games like Kick Ass Kung-Fu.
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The Real and Virtual Environment stand in a spatial relationship to each
other. In augmented reality, real distances mostly correspond to virtual space.
For example, in the game Ruptured Skies (Schmidmayr, 2003) the player steers
a virtual airplane with his arms held out to the side. His arms correspond to
the wings of the plane. By moving his outstretched arms to the left, the airplane veers to the left. In this respect, virtual distances correspond to real distances, and even real angles are reflected in the virtual world.
There are no side-scrolling games in AR yet, where the virtual world moves
independently from the real world.
There are, however, applications in which the scale of the real and the scale of
the virtual world differ. Augmented games allow the player to experience
such differences in scale much more directly than he could in computer games
such as Populous, Battle Isle or Sim Ant.
Imagine a table-top projection game on which a green landscape with abundant vegetation is displayed. On the table, there live a herd of creatures which
the player has to look after. In relation to the virtual landscape, the player is
giant-sized. This corresponds to his in-game role as a sort of minor God who
takes care of his creatures.
The perception of real distances, in relation to the game, is influenced by the
display devices of the game. The player can look down on a table-top projection, making him all-seeing, bigger than life and in control, while an HMD
severely limits his vision and, with it, his overview and omniscience in the
game. Alternatively, a projection on the ceiling can force the player to look up
occasionally, making him feel watched or threatened. This experience can be
enhanced with an occasional scary noise emanating from somewhere nearby.
The possibilities of positioning feedback, be it visual, audio or haptic, inside
the game space are endless.
The Virtual Representation of the Player defines what role the player takes
on in the virtual part of the game. In computer games, the player acts either as
himself or is represented by a virtual avatar. In most casual games, the player
has no virtual representation. In puzzles and click-and-point games, but also
in strategy games and God games, the player can imagine himself as being
free of restraints in manipulating the world or commanding his minions. In
many computer games, avatars are used to draw the player closer to the vir-
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tual world. The player can control the avatar and influence his actions, with
the result of forming a kind of emotional relationship or even identification
with the virtual representation. Avatars are employed in story-driven adventure games such as Larry and King’s Quest, third-person action-adventures like
Tomb Raider and World of Warcraft, as well as in numerous other genres where
characters evolve throughout a story.
In augmented reality, avatars can be used to assign a robot, a car or other controllable entity to each player. However, in AR it is often not necessary to draw
the player into the virtual world. Instead, he can be immersed in his real surroundings, as is the case in physical, full-body games. Other AR games that
focus on short and intense interaction, casual puzzles, quick stimulusresponse or social challenges do not require the player to be represented by an
avatar in the virtual part of the application either. If an augmented game
tightly incorporates both the real and virtual world, an avatar would only remind the player of the difference between physical and digital. When the
player is no longer aware of the divide between real and virtual, an avatar can
even be bothersome and distracting.
Virtual persons might be better suited as advisors and guides who explain
game rules and dynamics to the player where necessary. However, such tutors
should only be employed sparsely. They should be avoided wherever simpler
rules, better interfaces and other self-explanatory content can be used instead.
3.2.1.1.2. The Temporal Dimension
The story of a game can be played out in a matter of minutes, hours or occasionally even days. Action and reflex games take only minutes, while strategy
games based heavily on complex decisions can last for hours, and “live-action
role-playing” games (LARPs) that are played in the real world can even span
over several days.
The length of the story of a game should be adapted to the time that players
are willing to spend playing, the location of the setup and the effort it takes to
interact. For example, passersby in a shopping mall might be prepared to play
for ten to fifteen minutes. They might enjoy engaging other players. However,
they will not want to play a physically challenging game that makes them exert themselves and start sweating.
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The smaller the intensity of an interaction is, the longer a game can last. When
the player does not have to concentrate intensely and does not have to focus
on numerous different aspects of a game, but can relax his mind or take a
break once in a while, the game can last longer. For example, there are some
GPRS games that give players several days to reach a certain destination. In
Fishies, players can leave at any time and the concentration required is so
minimal that it is not necessary to have short rounds with clearly defined
goals. Games with such a loose temporal dimension could be referred to as
“ambient games”.
Arcade games intend to attract passersby who only have a limited amount of
time to spend. Rounds in these coin-up games usually last somewhere between 60 and 180 seconds. This time is packed to the brim with incentives,
visuals and action-packed interaction with the aim of having the player come
back for another round.
In general, AR games can learn about timing from arcade consoles. However,
augmented games can also use portable or ambient setups that can involve the
player over a longer stretch of time. Additionally, as mentioned before, interaction should not be too simple to avoid mindless games focused on addiction
and monetary gain.
The time within a game does not have to adhere to the passing of real time.
The player can experience a story that spans over months within the game in a
couple of hours of playing. In Peter Molyneux’ game Fable, the player’s hero
even ages from childhood to adolescence in the course of the game (Figure
3.9).
Figure 3.9: In Fable, the player guides his character from childhood to old age as
the story progresses.
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Alternatively, game time can correspond to real time. In these games, the
player is often focused on stimulus-response and strategies that he has to employ.
Time in games can even be slower than in real life. This allows the player to
experience a world in slow motion or view it from the eyes of a fly.
The passing of time does not have to be fixed. A game can bestow powers of
time manipulation on the player. He might want to speed up the game when
he is traveling or slow it down to consider complex situations. The game itself
can intentionally change the pace of a game by manipulating time. If a player
has less time to react to obstacles or for making decisions, he is challenged to
concentrate harder and to react spontaneously, rather than being allowed to
ponder his options.
A particular kind of time segmentation can be found in turn-based games.
These games do not simulate the passing of time, but only display stages of
the game. A turns is a fixed state in which the player changes the game world.
Many strategy games use turns to allow the player to master situations of
growing complexity. In Sid Meier’s Civilization, the player manages a growing
civilization from the first settlement to world domination. As time progresses,
he has to manage more and more resources and make decisions for each city
and unit. The time required for this process increases with the progression of
the game. However, the time that the player takes to complete each turn does
not matter, because the game only differentiates between turns. In the next
turn, the game computes the effects of his actions. This is continued until the
player has reached a victory condition or has lost the game.
3.2.1.1.3. The Social Dimension
The contact with others is very important to players (Trappey, 2005) and
should be fostered wherever possible. Socially oriented games sometimes
include challenges solely to get players together. The story of the game itself is
secondary and just a means to congregate players. In a playful way such
games allow social conduct that even eludes norms outside of the game. They
allow players to express themselves and get to know each other in unusual
ways. A prime example is Activity, where participants work together to guess
the meaning of charades, drawings or descriptions. Even though Activity requires some knowledge and skills from the players, these skills are not essen-
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tial for the entertainment and fun that the game provides, because the main
focus of the game is on the social level.
Augmented reality is an ideal medium to nurture social interaction. Augmented games let people come together in a shared physical space, participating in a fantasy world in collaboration. They can share a gaming environment and explore the possibilities of the augmented world together, challenging them on both an individual level and as a group (Magerkurth, 2004).
Together, they can overcome problems or face them in playful competition,
enhancing the gaming experience. It would seem a waste of opportunity not
to include social interaction in an AR game. Its shared environment enables a
gaming experience that ordinary computer games cannot offer.
Emotional Depth varies from game to game. Losing at a board game when
playing with friends can enrage or humor us, can cause laughter or shouting.
Computer games on the other hand, are often focused on a screen and players
are essentially alone in their physical surroundings. Even in online multiplayer games, social freedom is often limited to communicating via text and
speech (Turkle, 1984).
Most computer games do not intend to create emotional depth. Instead, they
address the desire for superficial entertainment by providing fast-paced action
with simple point-and-click interaction and screaming visuals inside a shallow
story.
In this regard, many computer games are comparable to shallow action movies. They serve as a means of light-hearted entertainment that do not require
too much emotional involvement of the viewer. Still, shallow action movies
are a valuable part of the scope of films because of their entertaining and superficial nature. However, if all movies were action movies, a major part of the
emotional potential of film would remain untouched.
Naturally, not all games are limited to superficial entertainment. There are
notable exceptions such as Half Life which manages to combine a first person
shooter with a complex and subtle story that is made totally captivating by
excellent storytelling. In Half Life, emotions such as fear and anxiety are unusually intense. These primal emotions are also the focus of horror games like
Resident Evil. However, if these games are comparable to movies, they reflect
the genre of B-movie horror thrillers (Figure 3.10).
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Figure 3.10: Some games like Resident Evil go beyond shallow entertainment
and confront the player with emotions commonly found in horror movies.
An exclamation of emotion while playing like crying or cheering, is extremely
uncommon. A player jumping up from the computer, screaming in jubilation
would seem inadequate, at best, to people around him. This is because the joy
that the player experiences is not shared by other people in the vicinity and
would probably cause alienation to a certain degree. It is this environment of
secluded play that takes much of the emotional and social experience from
playing computer games (Szalavári, 1998).
Augmented Games stimulate the full scale of emotional reactions that board
games, physical competitions and social games induce. It is only a question of
design to make use of these emotions. Games and players have to contribute
to an environment of openness and respectful understanding, in order to
allow each participant to forget the world around him and become willingly
absorbed in the fantasy of the game. To achieve this, a game has to foster
positive social experiences. Socialization, however, takes time and the players’
attention. A game that is particularly social must give players time and space
to communicate and socialize. Parts of the game that are not relevant to the
social experience have to be reduced and simplified.
The Number of Players and Participants influences the social experience.
Augmented games are predestined for multi-player applications. The number
of players is interlinked with the physical dimensions of a game. It defines
how many people can interact with the game and with each other.
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In general, fewer players will have a more intense and personal experience
when playing together. The game can focus on their individual input and
change the game world in an immediate and noticeable manner. On the other
hand, a player in a larger crowd will feel like contributing to a whole. He can
be part of a bigger group and identify himself with the achievements of all its
members. However, individuals in a crowd tend to have a more superficial
relationship with a game and be more willing to leave at any time.
The number of participants is not limited to the people who can control the
game as players. Especially in social games, spectators can give support and
enhance the fun, e.g. by commenting or giving hints and tactical recommendations. They can help the players of a flight simulator to navigate or give
clues in puzzles and quizzes such as Buzz and You Don’t Know Jack. Spectators
can also actively participate in a game. In Neon Racer, they can directly manipulate the physical surroundings of the game, thus shaping the racecourse
for the primary players.
Competitiveness is also rooted in the social dimension. Social play can be
encouraged by competition and cooperation. Players can form competing
teams or work together on cooperative missions that are fought against virtual
opponents. Common examples are games that involve strategy elements, e.g.
Masters of Orion, Dark Age of Camelot and Counter-Strike.
In cooperative games, opposition is created by the game in the form of AI
enemies, level design, plot twists, puzzles and other challenges. Board games,
for example, rely mostly on level design and chance. The board game Hugo
uses an enemy figurine, Hugo, the ghost of a haunted castle who moves according to the roll of the players’ dice. Hugo is moved by the players, but his
moves depend solely on the random throw of the dice. Whenever Hugo
catches a player’s figurine, it is trapped in the castle’s cellar. Players try to escape the ghost by hiding in the rooms of the castle. The game focuses the
players’ attention on Hugo and creates tension through his unpredictable
movement. In this manner, Hugo is basically an AI opponent.
Real opponents create more diversity and unexpected challenges than AI
players. Real players are especially valuable to AR games because they offer
varying challenges, they are unpredictable and enhance the social experience
with communication, criticism and curses.
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Increasing the number of participants induces group behavior. There are many
psychological influences that should be taken into account when designing
social games. Players can can choose to elect and follow a leader, to take sides
and enhance competitiveness, or they might act out personal problems within
the game, etc. The game designer should investigate the psychological theories on group dynamics and make use of this knowledge when navigating
large groups of players within a game, in order to to keep competition playful
and enjoyable.
Make-Believe Play allows the player to become absorbed in its fantasy. It
allows him to focus his actions and his awareness entirely on the game
(Csikszentmihalyi, 1977). The player can lose himself in the game and act
solely according to its rules (Caillois, 1961). He chooses to be part of the game
and act outside of the “ordinary” world. While playing, he is inside a makebelieve world where common social expectations are not applicable. The
player leaves behind the responsibility of having to behave according to social
norms (Honigmann, 1977). He can act out fantasies in the make-believe world.
This is especially important for adults, because for grown-ups, make-believe
play is only appropriate in special situations such as in art, acting and charades, at parties and within certain groups (Handelman, 1976). In this regard,
games are a playground for the mind, allowing the player to sidestep norms
and do something extraordinary.
Most games allow the player to act out fantasies inside the game world. Some
games focus on letting him experiment with dark desires and socially disdained actions. The computer games Dungeon Keeper and Evil Genius put the
player in the role of an evil overlord who has to manage his dungeon and hire,
train and discipline minions to fight the ‘bad’ heros who attempt to steal
treasures and to prevent the player’s goal of world domination (Figure 3.11).
Private and Public Spaces can be available to the players. AR games can employ classical real-world game-play where players socialize and compete in a
shared physical space. Additionally, players can participate from remote locations by utilizing network and tele-conference technologies such as 3D Live
(Wolfmaier, 2003; Barakonyi, 2004). Additionally, each player can have his
own private area within the game space (Kruger, 2003; Tse, 2003). This allows
the game to display personalized information that can be secret or relevant
only to a specific player or in a certain context (Szalavári, 1998).
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Figure 3.11: In Dungeon Keeper, the player takes on the role of an evil overlord
who can drill his minions to fight against treasure-robbing heroes.
AR offers many individual feedback channels to address players individually.
Amongst the most well-known are HMDs and other portable displays like
PDAs (Szalavári, 1998) (Figure 3.12). Furthermore, directional sound sources,
vibrating chairs and countless other feedback channels can deliver information to players on a personal level.
Figure 3.12: AR can display personalized information to each player.
In Mahjongg, the tiles of other players are hidden from view.
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3.2.2. Input and Feedback
The true quality of a game lies in its interactive and immersive quality. Its
strength is to let the player imagine himself a part of the game world and experience that world with his entire awareness. A big part of the experience of
being inside a game world stems from the player’s options to manipulate the
world and experience the effects of his actions.
The way in which the player can interact with a game is generally referred to
as the interface. The interface focuses the player’s attention, channels his freedom to affect changes in the game world and gives him feedback on these
changes. It is the central element of the player’s interaction with the game. The
crucial role of the interface, not just for games, was expressed by Hix and
Hartson (1993) in the words, “To users, the User Interface is the system”.
The interface affects the player’s emotional experience during the game. For
example, a game that takes place in a science fiction setting might utilize displays embedded in metal frames. It may allow the player to control the game
with his hands and arms by placing them in moveable exoskeleton sheaths.
The aesthetic design of these interfaces, as well as their mechanical look support the atmosphere and communicate it to the player.
When transporting an existing computer game idea to an AR setting, a new
interface has to be designed. In most cases, the original game was made to be
purely virtual and run on mouse and keyboard. In AR, these restrictions no
longer apply and the creation of a unique interface is part of the AR design
process. Haptic alternatives to mouse and keyboard can be found which feel
entirely different from working on a PC. The mode of interaction can be
changed from virtual to real or any kind of hybrid between these two alternatives. This can greatly influence the dynamics of the game as well. For instance, the Solitaire PC game is a point-and-drag card game played with only
the mouse. It could be transformed into an AR projection-based game that
tracks the player’s fingertips. The game would still be using the same pointand-drag interaction. Simply tracking hand movement would not make use of
the extended possibilities of an AR space. The player could use several fingers
or both hands at once, even play together with other people. Yet, none of these
possibilities are inherent in the game dynamics of the PC version of Solitaire.
The game dynamics need to be adapted to suit the new form of physical inter-
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action. Thus, the technology offers new possibilities that demand a change in
game design.
To use custom interfaces in a game with due finesse, it is necessary to analyze
existing interfaces and the way they shape the player’s emotional experience.
In general, every interface consists of input and feedback channels.
Input channels determine the ways in which the player can communicate his
wishes to the game. He can control its flow by making his decisions known to
the game. Input can be primarily physical like body movement, haptic such as
buttons, and acoustic like speech.
Changes in the game world are reported back to the player via feedback channels. Feedback, too, can be visual, using screens and projectors, acoustic like
sound effects to mark a certain event, and haptic like force-feedback vibration.
All of the information that is relevant to the player in the course of a game
must pass through input and feedback channels, as Shneiderman stated for
interfaces in general (1998). No information outside the feedback channels can
reach the player, nor can the player influence a game but through the input
options that is available to him.
When a player first approaches a game, the feedback channels inform him of
the rules, for example by displaying an on-screen tutorial and a blinking
“press a button to start”-image. Then, the game waits for input which the
player in this example delivers by pressing a button. The game will inform the
player that the press of the button was successfully registered, e.g. by playing
a sound and displaying the start-screen of the game. Throughout the course of
the ensuing game, player and game continue to communicate through the
available input and feedback channels.
The player needs to perceive how the game is responding to him. He must be
able to figure out a causal relationship between his input and the feedback he
is given. In a game, a certain action has to trigger a repeatable and foreseeable
response. This allows him to plan his actions in order to achieve his goal. If
each response were different, the player would not see a connection between
his action and the feedback of the game. Responses from the game need to be
consistent (Krueger, 1991). The feedback has to be closely related to the input,
both in the time that passes between input and feedback and in their logical
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coherence. Feedback should be immediate and clearly related to the input that
was just given.
All possible input and feedback events of a game need to be analyzed. Every
possible input has to cause a suitable response from the game. The continuous
flow of input and feedback must never ebb or break. If the player is left without a reaction from the game, he will assume an error.
Planning a game’s input and feedback responses leads to a sort of storyboard
that can give a good overview of the options that the player has and the complexity that the game has to support. Being aware of the complexity of the
input and feedback of a game is especially important in early stages of development. Programmers and designers can decide which features are crucial or
easy to implement, and which ones should be dropped because they would
take too much time in development while offering only a small benefit to the
player.
3.2.2.1. Levels of Interaction
In AR games, input and feedback channels can be focused on either the virtual
or physical space. An example of primarily virtual input is when the player
controls a virtual avatar with mouse and keyboard. The physical world is the
focus of the player’s input when he has to move around or interact with real
people and real objects. Similarly, a game can focus its feedback on a virtual
level, e.g. HMDs or PDAs, or in the physical space, using force feedback or
other mechanical actuators.
Besides virtual and physical space, interaction can take place on a conscious or
subconscious level (Figure 3.13).
Conscious input is committed willingly and in full mental control, such as
when pressing a button or moving around an object. Subconscious input analyzes parameters that cannot normally be controlled by conscious thought
such as the player’s posture, his heart-rate and other biometric parameters.
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Figure 3.13: Input and feedback can focus on the real or the virtual world and
on a rational, conscious level or an emotional, subconscious level.
Feedback, on the other hand, delivers information to the player, so he may
analyze a problem and draw logical conclusions before giving his input. Two
classical examples of consciously given feedback are the display of a healthbar or a timer. When the health bar is low, the player is signaled to avoid
danger. When the countdown is approaching zero, he knows he must hurry to
reach his goal. Subconscious feedback is the attempt to directly affect the player’s
emotional state, while avoiding a conscious analysis of the presented information. Colors, images and sounds cause emotional response, for example,
soothing chill-out music or unsettling horror-movie imagery. Means to evoke
emotion are employed in advertising, in film, architecture, computer games
and most other genres of art and design. AR has the additional option to use
haptic feedback. A cold burst of wind and a splash of water, combined with
the creaking of wood planks emanating from the floor, can make a sailing
game intensely more emotional than it could ever be on a computer screen.
Add to this a feeling of vertigo, caused by electrodes affecting the vestibular of
the inner ear (Maeda, 2005), and the challenges of sailing face the player headon.
In general, it is best to focus on a single conscious dimension for each input
and feedback channel. For example, in a two-player tactical game, participants
have to construct a pipeline from point A to point B before their opponent
does. The game uses HMDs and employs primarily visual feedback. As a result, the player’s attention is on the display device. To avoid distraction, all
relevant tactical information like a game map, the next pipeline tile the player
has to place and so forth, should be conveyed on the conscious visual level.
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Acoustic and haptic feedback should only serve to enhance the experience
emotionally. For example, the background music might support the game’s
pace by matching the players’ heart-rate. To avoid confusion, no tactical announcements like “Your next pipeline-tile is curved” should be made via the
acoustic channel.
A further advantage of focusing on limited input and feedback channels is
that the interaction is easier to design and balance. When fewer technologies
interact inside a game system, development, testing and maintenance also
become much more manageable.
3.2.2.2. Choosing a suitable Technology
Modern PC games have been sporting technical features and better graphics
as a point of sale instead of idea, emotional appeal, story and challenges. AR
applications have been following a similar trend of putting technology before
interaction. Naturally, it is easier to advertise a new technology than it is to
present the fleeting satisfaction gained from a novel interaction-technique,
because the effects of better hardware can be measured more easily.
It is often tempting to use a well-tested, existing interface and attempt to combine it with a completely unrelated game idea. This is one of the most common problems in current AR prototypes. However, if the game idea is not
suitable for the interface as it is, either the hardware or the idea will need to be
revised. For example, if 2D visuals are insufficient to convey appropriate feedback, it is necessary to find an alternative and more suitable display technology.
Of course, interface devices can also be designed without a specific game in
mind. Many interface technologies have been developed to test an idea, rather
than to create a game. For example, a PDA equipped with a video camera can
augment captured video with virtual content (Figure 3.14). This makes an
enormous variety of applications possible (Wagner, 2005). Furthermore, PDAs
constantly get user feedback from all around the world which helps to improve the interface. This refines the interface in general and thus makes future
games on the PDA better.
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FIgure 3.14: Interface devices like PDAs can be used for a wide variety of applications and games. Camera images are augmented with virtual content to create
the game Invisible Train.
The challenge in creating a game for such an interface originates from the fact
that each game has its own features, commands and hardware requirements.
A PDA can be adapted to suit a specific game by leaving out unnecessary
hardware or enhancing the interface with game-specific hot-keys, gestures and
buttons. This way, requirements for the game are met, while benefitting from
all the improvements that already exist for the PDA.
It is generally a good idea to preserve proven genre-specific concepts in new
games. In a Jump and Run game, the right-arrow should move the virtual
character to the right. In a shooter game, conventions used in PC games like
common weapons and their effects should be maintained. Of course, the
keyboard-control from shooter games does not need to be adapted. It might be
better to find alternative input devices all together. When making an augmented board game, it might be a good idea to keep the turn-based interaction
or the physical figurines. Equally, in strategy games, the point-and-click metaphor is so embedded in the player’s expectations that it should be kept in one
way or another. To achieve this, Magic Land (Cheok, 2005) uses physical plastic
cups to pick up, place and move around virtual characters on a table. This creates an intuitive means of interaction in the AR setting, while maintaining the
point-and-click metaphor for players who are used to PC games (Figure 3.15).
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Figure 3.15: The setup of Magic Land uses cups to pick up and move virtual
characters. This creates an intuitive means of interaction, while maintaining the
point-and-click metaphor of computer games.
3.2.2.3. Input Dimensions
Input channels are the means to let the player influence the game world.
Through the input, the game receives information from the player and reacts
to it. The visual design of input elements should mark them as being manipulatable (Groiß, 2003). Buttons are meant to be pressed, knobs and handles
can be turned, pressure sensitive plates need to look robust enough to step on
and so forth. Input elements that are designed to be visible and recognizable
allow the player to understand what he can do to influence a game.
A manipulatable input element also needs to convey the effect it has on the
game. A button might do anything, while a big, red button with black and
yellow stripes encircling it might be used to destroy something. Similarly, a
lever might affect any number of things, but if it is placed in the visual surroundings of the console of a flight simulator, it might be interpreted as a
thrust control. The design and placement of input elements can make them
self-explanatory and give the player an idea of what he can do to influence the
game (Nielsen, 2004; Krueger, 1991).
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The technology of AR is very complex, however, this complexity is not handed
on to the player. Augmented games may even address people who do not
normally play on the computer. When the technical parts of input devices remain hidden, the player does not need to be familiar with current technology
to play the game.
The most important input elements are those that the player needs most often.
The input channels should be efficient for repetitive tasks and not require the
player to do things in a complicated manner, similar to Huffman-coding
(Huffman, 1952). For example, an action-adventure game, in which the player
controls a hero, has an inventory of different items like weapons, potions and
armor. Potions are needed often to heal or restore energy. In this game, to gain
access to his supply of potions, the player has to press the Escape key to open
a menu, select the ‘Inventory’ entry and then the ‘Potions’ entry and finally
the potion he needs. This would be a logical but inefficient way of offering the
player access to his inventory. Instead, many PC games employ a “quick bar”,
onto which items can be dragged that can then be accessed by pressing the
number keys (Figure 3.16). In this case, the number keys act as hot-keys. They
allow the player to activate commands without having to navigate menus.
Hot-keys can also be used to bring up menus, repeat the last action or switch
between button layouts.
Figure 3.16: Repetitive actions should be simple and efficient for the player. One
way to achieve this are quick bars. Neverwinter Nights uses three stacked quick
bars which can be accessed by holding down the Shift and Control keys.
Important input elements should be clearly visible and easily accessible (Apple, 2002). For instance, a certain game has two buttons which are equally necessary for playing and, additionally, one button to start and end the game. The
two important buttons could be big and centered, while the start button might
be smaller and placed apart. Of course, the placement depends on the design
of space and the atmospheric style of the setup. Wherever possible, the most
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obvious input elements should lead the player to a complete and enjoyable
gaming experience.
Furthermore, different input elements have different effects and should be
placed accordingly. They can be grouped into clusters of related elements to
facilitate navigation. These clusters can be placed according to their meaning,
e.g. attack, communication, decision making, visual effects or magic.
A general theory of how to place elements within an interface can be found in
the field of “Neuro-Linguistic Programming” (NLP). Its basis is a correlation
between brain activity and eye movement. For example, when trying to remember an image from the past, the eyes tend to look to the upper-left corner
of their field of view. Pondering a situation to reach a decision lets the eyes’
attention drift to the lower right. This is used primarily in advertisement but
also in 2D interface design, e.g. the ‘OK’ button is in the lower-right corner
while ‘Cancel’ can be found to the lower-left. The theory can be useful in any
2D or 3D environment in the virtual or physical space. Whenever the position
of the player is known, visual input elements can be placed with respect to his
line of sight.
3.2.2.3.1. Physical Input
Physical input refers to body movement which is directly measured by a
game. The game interprets full-body movement like walking, jumping or doing martial arts. Hämäläinen (2004) presented Kick Ass Kung-Fu, a beat-em-up
game that can be played in a large training area. On the left and right-hand
sides of this area, two large projection screens are mounted which both display the game. The game is similar to Street Fighter, with the exception that
players interact with their own body and fight virtual opponents by punching,
kicking and jumping around in front of the screens (Figure 3.18).
A similar mode of interaction is used in EyeToy. The package EyeToy Kinetics
focuses on physical exercise as found in a gym (Figure 3.19). A camera records
the player who moves around in front of a television set. The screen displays
the camera image overlaid with virtual information. An advantage of this
setup is that it is small, transportable and inexpensive.
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Figure 3.18: In Kick Ass Kung-Fu, the player battles virtual opponents with
physical movement.
Figure 3.19: EyeToy Kinetics also focuses on physical exercise, but uses a smaller
setup than Kick Ass Kung-Fu.
Physical input also refers to the use of parts of the body, limbs like arms, fingers and legs, lips and eye motion. Advanced physical recognition can analyze
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gestures like waving, pointing and shaking one’s head. The velocity of these
movements can also serve as input for a game.
Twister is an example for an off-screen game that relies mostly on physical
input of the limbs. The game’s setting is a mat with large dots of different
color. Every turn, each player puts either a hand or a foot on a certain colordot until he fails to twist all four of his limbs to match the pattern of randomly
selected dots.
A game can also interpret stillness, or absence of movement, as input. Sony’s
EyeToy package contains a game in which the player takes on the role of a secret agent who has to avoid detection by staying motionless when a spotlight
or security camera passes near his position. In AR, it is not possible to restrict
the player’s physical movement arbitrarily, but it is possible to give him positive feedback when he stops moving for a while.
A game may also interpret the overall physical shape, size and posture of a
player. Starner (2000) mentions the possibility of using bio-signals like the
heartbeat or moisture of a user’s hands, i.e. the skin conductance level, to influence the speed and difficulty of a game. A study has been presented by
Holger Diener at GDC 2005 in which users were monitored during a game of
Tetris. According to their emotional state, the Tetris game adapted its speed,
likeliness of certain pieces falling, the reliability of the keyboard and other
parameters. Players were enraged by an unreliable keyboard and too high or
low game speed. In effect, the study seems to show that improperly balanced
game parameters can easily cause anger. This suggests that balancing a game
should not depend too much on the player, but that a well-rounded experience is formed according to game design aspects.
3.2.2.3.2. Haptic Input
For haptic input, the measurement of movement is mediated by objects. Haptic input devices include buttons, mouse and keyboard, pressure sensitive
floorboards, musical instruments, ARToolkit markers and many more. A keyboard does not necessarily have to be made of plastic. There are several approaches to project the buttons visually onto a table’s surface. The user’s fingers are tracked, allowing him to type directly on the table. One example is an
all-in-one box that displays the keyboard layout with red laser-light and registers the fingers when they occlude a laser-beam (Figure 3.20).
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Figure 3.20: Keyboards and buttons do not always have to be made of plastic.
The laser keyboard projects the button layout onto any flat surface.
In the installation Psychic Space, Krueger uses a room, entirely filled with pressure sensitive tiles, on which the user moves around to trigger responses.
Similar hardware setups have been used to design AR games, mostly based on
transporting computer game ideas like that of Bomberman (Figure 3.21) and
Space Invaders to augmented reality (Velikovsky, 2004; Zhou, 2004).
Figure 3.21: Pressure sensitive plates can be used to locate players. Computer
games such as Space Invaders and Dyna Blaster have been adapted to such a setup.
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Ishii (2002) and Piper (2002) use sand and clay to model a surface in the real
world. The surface is overlaid with projected information, containing geological data like height, slope and even virtual water-flows (Figure 3.22). When
the user alters the surface, the projected information changes accordingly.
Such an interface could be a powerful intermediary for AR tactical strategy
games, in which players change the physical landscape to control virtual
agents (Barakonyi, 2005a).
Figure 3.22: A physical surface can be modeled in Sandscape. Virtual information
like height and even virtual water-flows can be displayed on the surface.
Interfaces that require physical exercise are becoming more popular, as tracking becomes faster and more accurate. In Legible City, Jeffrey Shaws (1991)
used a bicycle, fixed to a mount, to navigate a 3D space which was displayed
on a projection screen in front of the bike. Marnix de Nijs (2001) adapted the
setup to use a treadmill instead of a bicycle (Figure 3.23).
Figure 3.23: Virtual displays combined with physical exercise in Legible City
(left) and Run Motherfucker Run (right).
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To encourage physical movement, Weilguny (2006) employs a punching bag
that reacts when it gets hit, cursing or screaming when a punch jolts an embedded motion sensor. The fitness application could be made into a game by
extending it with challenges and incentives. The player might have to hit certain areas or use specific kicks and punches to unlock different sound sets.
On the consumer market, there are currently a few consoles like the Playstation, that have extended their virtual on-screen games with physical and haptic input devices (Marks, 2001). Besides unmediated physical exercise as offered by EyeToy, musical instruments are very popular like drums, guitars and
bongos (Namco, 2006; Nintendo, 2005; RedOctane, 2004) (Figure 3.24). These
input devices are simple and intuitive, making the games more accessible and
thus easier to sell (LA Times, 2004). In the words of an online review for Nintendo’s Donkey Kong Jungle Beat:
I was skeptical about the controls for Donkey Kong Jungle Beat, but
when I decided to give it a try, I was dumbfounded at how amazingly
well they work. In fact, this game breathed life into the dying genre of 2D
side-scrollers because of the amazing control.
(cikesef on rr.cube.ign.com)
Figure 3.24: Musical instruments are employed in many commercial console
games. Donkey Kong Jungle Beat uses plastic bongos as a controller.
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Self-explanatory haptic input devices that are well designed, can transport fun
and casual entertainment very quickly. Simple devices and intuitive rules keep
the learning curve low, no matter if the input device is a Taiko drum or a
Teddy-bear robot (Sekiguchi, 2001).
Sadly, less technical devices like common toys (see Chapter 2, Section 3.7
“Toys”) are not yet used in AR games often. Softballs or rackets, playing cards
or paint-balls, dolls or building blocks can enrich physical interaction with
their tangible and familiar nature. Any input device that is easy to use will
allow the player to apprehend the game quickly. As a result, he will have more
time to enjoy and explore the game.
3.2.2.3.3. Audio Input
Acoustic input can be analyzed for a variety of features. The most common
attributes are outlined here.
• Loudness: A sounding body transmits energy to its surroundings. This causes
variation of air pressure at a certain point in space, referred to as loudness
(Randel, 2003). The perception of loudness is different for individual people,
for different times and emotional states as well as prior influences on the ear,
partial deafness, etc. Perception also depends on the background noise and
on the frequency and duration of the sound (Weber, 2006). Common ways of
volume-based interaction are shouting, whispering, banging pots and pans
or creating noises with other objects.
• Frequency: A more refined way of analyzing acoustic input is to distinguish
between different frequencies. Low frequencies are generally referred to as
bass. The human voice is most present at mid-frequencies. High frequencies
give distinctness, sharpness and texture to perceived sounds. For instance,
frequencies can be used to distinguish voices from background noise, singing from screaming, etc.
• Direction: Human ears can locate the origin of sounds. Sound waves hit the
earlobes at a certain angle. Because sound takes time to travel through the
air, the left ear may perceive a sound slightly before the right ear does. This
mechanism, along with other factors, lets humans perceive the direction
from which sound waves arrive. As a result, sound waves that are reflected
by glass walls are perceived to originate from the wall and not from their
actual source. This can be used in the design of space, to give the player a
heightened or even contradicting perception of sound. Devices that are em-
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ployed to convey direction include stereo speakers, surround sound setups
and headphones.
• Duration: The duration of a sound is simply the length of time between the
first and last continuous occurrence of a certain sound. Duration can, for
instance, be used to estimate the size of a screaming person’s lungs.
• Timing: The flow of volume, frequency and duration come together to form
rhythm, suspense and emotion. By analyzing all acoustic factors in combination, sound events can be appreciated in more detail. Timing is essential in
judging the rhythm of clapping, the order of notes played on a keyboard or
even the quality of someone singing to a certain kind of music. Between
sounds, there is always a transition, during which one sound passes into the
next. Sounds can also be morphed into each other, to create a more dynamic
transition. Morphing is also used in image processing, where two images
flow into each other according to certain parameters.
Conscious Audio Input is generated by the player willingly. He can employ
his voice or use his own body as a percussion instrument, e.g. clapping,
stomping, snapping fingers.
In an AR setting, the player’s acoustic input is always overlaid with some
background noise. It is difficult to filter the noise from the actual input. Loud
and clearly defined input can be more easily recognized by the system.
Voice input can be processed to act as a speech command. The player can tell
his phone to call mother, order a game to turn off the lights or a radio. Speech
commands can also affect only specific game elements. For instance, the
player might order a robot around by speaking: “forward, left, right, fire”. In
this case, the command “fire” could also be called “shoot” or “attack”. If the
game only recognizes “fire” and the player says “shoot”, then he will deduce
that he probably cannot shoot a gun in this game or if he is technologically
knowledgeable, blame the poor speech processing. To avoid this, the game
must consider alternative words that the player might wish to use and include
a complete list of synonyms for each possible command (Christian, 2006).
Additionally, words can mean different things in different contexts. When a
player controls a robot that drives on chains or wheels, the command “left”
will most likely refer to “turn left”. On the other hand, if the command is
given to a humanoid, it might imply “step left”, “continue moving left” or
“turn left”. In such a case, the game has several options to offer alternatives. It
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can use commands that are not ambiguous like “clockwise”, composite commands like “walk left”, reduce the options of the player to affect the game
element or control it in a way that is not based on acoustic input.
Conscious audio input can be the basis of games like Karaoke, a sing along, a
dreamy music-star competition or a test of masterhood in cursing in fake
Japanese. Another example game would be a children’s fairy tale game, in
which a wall-sized projection displays the colorful world of a fable filled with
all sorts of animals. The game is like an illustrated, interactive version of children’s books that progress from scene to scene. The players take on the roles
of animals like cow, a cat, a dog, a raven and so forth. As the fable progresses,
each player gives acoustic input to activate a cue from his chosen animal. For
example, the fox, the chicken and the dog are in a scene together. The fox
slowly sneaks up on the chicken. Children who are watching can scream
“woof, woof!” to activate the dog and make him bark at the fox to deter him
from eating the chicken. Then, the story continues depending on the decision
that the players have effected.
Ambient Audio Input which is not consciously made can also influence a
game. Examples include talking people who are not participating in the game
and the general background noise at an exhibition or in a museum. Conscious
input like clapping causes an echo that depends on the surroundings of the
game. This echo can be seen as the ambient part of the audio signal. As such, it
can be analyzed to enhance or distort the effect of the player’s clapping.
In general, ambient input should only affect ambient or subconscious feedback. For instance, the background noise in an installation could influence the
color tint of a background animation. The frequencies of ambience could influence weather patterns and cloud overlay in a strategy game. The tone of
voice of a player can influence how much a virtual gnome salesman trusts the
player and make it easier to haggle. A science-fiction action-game using headsets can analyze the player’s breathing and amplify it to achieve a spaceodyssey atmosphere.
Ambient noise can be turned into an integral part of the game. In a racing
game where the player competes against a computer opponent, the cheering
of real people who are watching the game could make the player’s vehicle
faster than that of the computer opponent. Through the backing of the spectators, the player gains a measurable and definite advantage in the game.
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However, it has to be clear to the player that certain elements of the acoustic
background influence clearly defined elements in the game. In the case of this
racing game, a visual meter could display the background volume and powerup graphics could illustrate its effect on the speed of the player’s vehicle. This
way, the ambient input is turned into a conscious input channel.
3.2.2.4. Feedback Dimensions
Feedback conveys changes in the game world to the player. Feedback is crucial to establish the illusion that a game reacts smartly and attentively to the
player’s actions. When he has affected an input, the game should show its
effects quickly and in a clearly understandable way.
The amount of feedback should convey a complete picture of the game. Details deliver an emotional experience and enhance the player’s understanding
of the game. On the other hand, feedback needs to be limited, so the player’s
attention is not disturbed by irrelevant details. Internal variables and compiler
exceptions do not need to be forwarded to the player (see Chapter 2, Section
3.5 “Complex Computation and Simple Rules”). In other words, what feedback would be given if the game device were magic?
Additionally, feedback informs the player about changes in the game world.
For instance, in a strategy game, the weather might influence the movement of
units. The game has to convey this via feedback channels, to inform the player
what state the weather is in and how this affects the movement. Visuals have
to clearly show heavy rain to be different from bright sunshine. Icons might
inform the player that movement speed for all infantry units is halved when it
rains, but vehicles move only 25% slower (Costikyan, 1994). Also, a weather
forecast might be necessary to allow the player to make tactical decisions
about his next attack.
Feedback also tells the player about rules and goals as well as his ways of providing input to the game. Amongst others, racing games, adventures and
strategy games expect the player to use certain routes, roads or paths. Each
game has different ways of achieving this, e.g. by placing walls and gorges as
physical limits, colored boundaries that mark a racetrack, flashing beacons
that act as waypoints, etc. The player knows that an obvious and clearly outlined path is one that will most often lead him to victory.
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The requirements of feedback channels are primarily influenced by the number of players and the dimensions of space. Depending on these, it might be
ideal to use either large, wall-filling projections, speech announcements, HMD
displays, table-top projection, vibrating chairs or PDAs, etc.
Feedback serves to illustrate the game’s fantasy world and enhance the emotional experience of the player. Graphical elements, appealing music and
countless details support the fantasy of the game. However, feedback cannot
be seen solely as an aesthetic means. It serves a purpose of communicating
relevant information to the player. Therefore, the importance of feedback
channels lies primarily in enhancing playability, interaction and flow for the
player. Myron Krueger stated as early as the 1970s, “The visuals should not be
seen as artworks, the sounds should not be judged as music. The only aesthetic concern should be the quality of the interaction.”
3.2.2.4.1. Visual Feedback
Visual feedback is the central element of most games. Computer and
projection-based games, board games and even athletic games rely heavily on
visually presented feedback. The number of a dice roll, the point where an
arrow hit its target and the position of a racing car are primarily made up of
visual information. Of course, and this illustrates the many dimensions of
feedback, a lot of information can be gathered through other feedback channels. The number of a dice roll could be determined by touch, the impact of an
arrow can be heard, as can the racing car. However, to gain complete and accurate knowledge of these parameters, visual information is essential.
Visual information is directly analyzable, but also as very emotional and
closely related to memory and imagination. Numbers, progress bars and coordinates can display accurate information. On the other hand, an emotional
level is touched when watching the sun set beneath reddened clouds, when
the rain drips off of a forest with countless, lush, green leaves or when recognizing the face of someone dear in a crowd of people (Figure 3.25).
The visual spectrum that can be seen by the human eye, has an enormous
range of colors, hues, intensities and textures. These visual attributes allow us
to distinguish between different kinds of information. For example, we can see
where one object ends and another begins, we can differentiate text from ornaments, we can tell surface color apart from depth and light and shadow.
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Additionally, we can judge distances between ourselves and other objects and
estimate the spatial relation of objects within our field of view. A multitude of
different information can be deciphered through the eyes.
Figure 3.25: Visuals can communicate abstract and encoded information (left),
but also immediately emotional scenes (right).
Focusing Visual Perception is essential to guide the player’s attention. Perceptual psychology states that the flood of information that we receive
through visuals needs to be filtered. We scan our environment to find information that is relevant to us. As a result, many details go unnoticed or are
registered only “in the back of one’s head”. In a game, there are also background visuals that transport the atmosphere and are not meant to be actively
perceived.
To assist the perception of the player, visual design can label information to be
of higher or lower importance. If the information that we receive is already
labeled as important when we see it, it will more likely be analyzed consciously. Information can be labeled by using bright and intense colors, memorable and unique shapes as well as moving or animated images. Visuals that
are closer to our center of attention and our field of view are also more likely
to be analyzed consciously (Figure 3.26).
Information of secondary importance can be displayed on the edges of the
player’s visual range, with small or semi-transparent icons, etc. Heads-up displays, menu bars and context sensitive information that can help the player to
find whatever he is looking for.
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Figure 3.26: The children’s game Zoombini does not use text to prioritize
information. Instead, items are color-coded, clustered and positioned around
the screen-area.
Context sensitive information is displayed in a particular circumstance or
when the player seeks more information. Many computer games use floating
textual information that appears when the mouse is over an icon, or is clicked
on a certain object (Figure 3.27). Other context sensitive messages can appear
when they are relevant to the course of the game, e.g. a flashing attackwarning or countdown. Additionally, the input possibilities can adapt according to the feedback information. For instance, when a player’s health is
low, he will want to use a health-up extra like a potion. In the game Fable, a
context sensitive hot-key is automatically assigned to using a life-potion
whenever the character is wounded.
Similar chunks of information can be grouped together to be easily recognizable. In a racing game for example, the lap time and current rank can be displayed close together when crossing a checkpoint because they offer tightly
related information to the player.
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Figure 3.27: Context sensitive menus display relevant actions in Neverwinter
Nights. When the player clicks on a friendly character, the menu is different
from that of an enemy or inanimate object.
Visual feedback can be grouped by using different areas, visual style, color
codes and other topical structures. For instance, a projection-based strategy
game could offer a touchable menu-bar near the top of the display area to
manage economy and construction, while all commands related to battles and
warfare are grouped near the bottom of the display. In addition, the economy
menu can be color coded a soothing yellow, while the warfare menu is kept in
a cold, grayish blue. These two modes of haptic input have created a setting
for the player and he knows that yellow information at the top relates to his
economic endeavors and blue information at the bottom to his battle plans.
When designing the games feedback, these two color-coded standards should
be taken as a basis. Any textual information about economy can be displayed
in yellow, as can buildings on the mini map that are not war-related and other
icons associated with resources.
Visual Feedback Devices which are commonly used in AR environments,
differ in how they transport information to the player. The input and feedback
devices in a game contribute to the emotional experience. Similar to the design
of space which is inherently visual, even if it does not actively deliver visual
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feedback. The shape and color of walls, the use of plastic or wood and of illumination. All design decisions add to the player’s emotional experience.
Moving gadgets, vibrating haptic devices, heads-up-displays and decorative
elements can strengthen the atmosphere of a game as well.
There is a vast range of predominantly visual feedback devices in augmented
reality. Firstly, screens that are used for computer games and television are
available in an AR setup as well. They include CRT and TFT monitors, large
plasma and LCD displays and TV sets. Each of these is known from other surroundings and is often associated with its original medium. For example, a
CRT monitor will be seen as the extension of a PC by most users, even if a
non-computer generated image is displayed on it.
Projectors can display visuals on a larger area than screens. Projectors come in
a variety of shapes and sizes, specialized on back or front projection, wide or
narrow angle, dark or bright surroundings. In projection-based AR games, the
setup is usually fixed to a certain space, because of the projectors, cameras and
the architecture which controls lighting conditions, the audio-visual environment and the flow of the players. In general, projectors are especially suitable
for larger areas, darker environments and several participants.
Inami (Tachi, 2003) presented a cloak fitted with retro-reflective material onto
which an image is projected. The image is a video of the real world, as seen
from the back of the cloak’s wearer. The video is captured by a camera behind
the wearer and the image is projected onto the front of the cloak. As a result,
the cloak appears transparent when viewed from the front (Figure 3.28).
Screens and projections can be made interactive by using image processing or
touchscreens. This combines physical input with visual feedback in a single
device for the player. Most touchscreens can only recognize the position of one
finger at a time. However, there are many approaches to create multi-user
touchscreens. Philips has presented a prototype of a flat, 30” LCD multi-point
touchscreen that is can be placed on a table and displays classical board games
(Hollemans, 2006) (Figure 3.29).
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Figure 3.28: Video image from Tachi’s retro-reflective cloak. A camera captures
the background and a projector displays the images onto the cloak’s surface.
Figure 3.29: Philips’ Entertaible is a multi-point touchscreen that displays
traditional board games.
Other very common display devices are head-mounted displays (HMDs). These
are usually light-weight plastic helmets with goggles, in which two small dis-
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plays are attached (Figure 3.30). Each display addresses one eye separately
which allows the game to display stereoscopic information to convey depth
information for a three-dimensional experience.
Figure 3.30: A head-mounted display provides separate information to
each eye, making stereoscopic vision possible.
HMDs can display information in the private space of each player. Thus,
games that employ HMDs can offer each player individual information that
should not be seen by his opponents (Szalavári, 1998).
A significant drawback of head-mounted devices is their weight and fragility.
The weight of most HMDs makes interaction that lasts for a longer period of
time rather strenuous on the neck muscles. Even in games that do not require
the player to move around much, HMDs should not be used for longer than
approximately 20 minutes. There is a risk of damage when the display slips off
the player’s head or is incorrectly taken off. To avoid effects such as these, the
player should not have to move around with significant physical effort in
HMD-based games (Figure 3.31).
Expensive technology like HMDs, also limits the number of players who can
interact simultaneously. Equipment has to be available for every participant.
Additionally, backup equipment is needed in case of hardware failures. All in
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all, fewer people can play when the equipment is complex, personalized or
expensive.
Figure 3.31: ARquake uses head-mounted displays. While HMDs can display
individual 3D graphics, the hardware is cumbersome.
Joe Paradiso mentioned another consideration about equipment that needs to
be carried around. At Siggraph 2000, he remarked, “We use the light switch
connected to the room instead of wearing a headlamp when we enter a dark
room. In the same way, we should try to create intelligent spaces equipped
with sensors, instead of carrying everything on us.” HMDs are usually employed to track the position of the player’s head and use that to calculate 3D
visuals. Newer generations of head-mounted displays weigh less and have
better displays. Still, the underlying problem that the user carries all the
equipment with him, remains.
Instead of delivering information directly to the user’s eyes, head-mounted
projectors display images onto the outside world (Tachi, 2003). A headmounted projector allows the position of the head to be tracked and used to
display 3D images on a real-world object. A similar approach has been used in
Virtual Showcase. The user’s head is tracked to adjust a 3D projection to suit his
point of view (Figure 3.32).
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Figure 3.32: In Virtual Showcase, the user’s head is tracked and 3D images
are projected onto a mirrored cone with correct perspective distortion.
All kinds of lights and lamps can be used as visual feedback devices. There are
spotlights and area lights to illuminate static elements (Figure 3.33). Moveable
lights such as scanners can be controlled by a computer to move in animated
sweeps or change color according to events in a game. Scanners are spotlights
with small mirrors that can be rotated to direct the beam of light (Figure 3.34).
Additionally, cutouts, called go-betweens or gobos, can be placed in front of a
light’s lamp to produce shadow-shapes (Gruber, 2004).
Figure 3.33: Static lights such as illuminated floor-boards (left) and LED-lights
(right) can be part of an interactive gaming-environment.
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Figure 3.34: Moving lights like scanners (left) and spotlights with moving
heads (right) can follow players or goal-objects in an augmented game.
Lasers and LEDs can also make the lighting of a game space more interesting,
when they are employed with care. Blinking, moving or reflected and refracted beams can be a supplement to certain events in a game.
Lights are mostly employed in architecture and on stage, but are of course
suitable for AR setups. They are a cost-efficient alternative to projectors, especially in cases where the visual complexity of images is limited. In these cases,
lights are cheaper, brighter and often more robust. Lights are ideally suited to
create a visual atmosphere with rich and intense colors. They can focus the
player’s attention by highlighting certain objects or areas of a game.
The First Impression at Public Spaces can attract potential player through
visual feedback. Potential players can arrive and leave at any time. They need
to be invited to approach the setup and take a look. People will stroll by, take a
peek at the game and be dragged on by their peers, unless the game immediately captures their attention. The player needs to be mesmerized, so he will
want to stay. The timespan available for this is usually no more than 20 seconds. Within that time, the game needs to make a good first impression. This
impression should correspond to the experience that the game can deliver to
the player.
The game setup needs to communicate the experience. Messages that a game
can formulate might be: “I am a magic book with cheerful stories for youngsters”, “I am an action-packed star-ship shooting-game that is great fun” or “I
am a tricky robot puzzle-game that will make you feel like a genius if you beat
it.”
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The first impression is mostly shaped by visual information. The setup space
and visual feedback channels are the best means to design a game to convey
its experience in a self-explanatory way. Firstly, the game setup has to be
clearly visible and easily accessible. Parts of the setup should be visible at all
times, even when a crowd of people is gathered around to play. Of course, a
crowd will also spawn interest in passersby.
Secondly, the design should present the most important and entertaining elements of a game. For example, the installation Gulliver’s World at the Ars Electronica Center is a complex assembly of different interactive terminals. The
central element is a large table with cups on it, faced by a large projection
screen that displays the scene on the table augmented with virtual figures
(Figure 3.35). Each cup on the table controls a virtual character. From this central element, the player can explore all the other terminals step-by-step. The
terminals allow the player to create his own characters from clay, change the
virtual landscape and even capture video recordings of himself to use as a
virtual character (Kato, 2005).
Figure 3.35: Gulliver’s World is an complex installation consisting of numerous
terminals. However, the user is guided by the structured design of space and
the use of visual interface-elements that give cues about their meaning.
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In general, potential players should be invited to experiment and play. A game
should welcome them and make them feel good about being there. For instance, players should not be alienated by by a complicated-looking keyboard
or by a clearly visible camera that is aimed at them.
Another method of welcoming new players is to employ friends, presenters,
guides, and info-screens that might sway people to investigate a game. Outside influences can also encourage users who are already interested in the
game, to take a closer look. They can help them to get a mental picture of what
the game expects them to do. Of course, one of the best ways of teaching the
game to new players is to let them watch others play.
3.2.2.4.2. Audio Feedback
Audio feedback enhances any gaming experience and is extremely important
to a game’s appeal. Sound and music are intensely emotional and support the
visual and haptic experience of the player.
Contrary to visual information, audio is not consciously analyzed by most
players (Trappey, 2005). Sounds are ideally suited to convey vague and emotional information: the feeling of stepping on creaking, aged, wooden floorboards, the intensity of icy wind blowing past scantly covered ears, the close
distance of a dangerously growling jungle-animal on a dark night. Audio can
be employed enormously well to enhance the emotional experience.
Sound can support or contradict the emotions delivered by other feedback
channels. In stressful situations during a game, the music can match the
strenuous pace with an intimidating tempo. Alternatively, the setting can be
juxtaposed with a slow, reverberating and foreboding melody. The intricacies
of combining music and sound with visuals and other feedback channels are
the subject of art and science, thus, only the cornerstones of employing audio
in games can be outlined here.
Audio installations can be very strenuous or even intimidating, due to their
direct emotional effect. Ikeda (2002) uses sterile sine wave signals and pairs
them with architectural design to produce patterns of echos. When users walk
through the space, their bodies cause acoustic reflections that alter the audible
sounds. In an installation entitled db, Ikeda uses a dark, anechoic chamber
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with low-frequency sounds and another, brightly lit, reverberating corridor
with high-pitched noise to create a unique emotional experience (Figure 3.36):
db is an installation consisting of two extreme spaces: a pitch dark anechoic chamber, and a corridor with over 100 fluorescent tubes reflecting
in its bright white walls. With the use of sine wave interferences among
others, Ikeda constructs multidirectional sonic pieces out of acoustic
waves and oscillations from low to high frequency, to be ‘physically experienced’ (rather than simply ‘heard’) in a nearly deafened state in the
anechoic chamber. In the other, whited-out space, the visitor experiences
bright lights accompanied by a single high frequency, which trigger a
rather cold sense of well-honed disillusion. (Ikeda, 2002)
Figure 3.36: Two architectural scenes from the audio installation db. The dark,
low-frequency room (left) and the bright, highly reflective corridor (right).
The emotionality and vagueness of acoustic information also has its drawbacks. It is difficult to clearly transport exact information without speech. Exact values like numbers or a percentage, the level of health, the number of
shots left in a gun and so forth are not suitable content for audio feedback. In
the PC game Fable, the player’s character can draw his bow longer to increase
the power of the shot. When clicking shortly, the character draws and lets
loose immediately, doing only limited damage. When drawing longer, the
bow is soon stretched to its maximum with the arrow inflicting a large amount
of damage. However, the only feedback given by the game about the exten-
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sion of the bow is a vague acoustic sample. No visual feedback is displayed on
the screen, no progress bar, no color-coded marker. Furthermore, the character
is invisible to the player when he is aiming his bow. Thus, the player is left
without exact information, while the virtual character and the game itself
know precisely the shot’s strength. As Adams (1998) points out, this restricts
the information that is available to the player for no apparent reason.
Some rather exact information can be delivered exclusively through audio.
Many games feature alarm sounds to warn the player of low health, a click to
indicate an empty gun, a jingle to signal the attainment of a new level of experience, etc. Weber (2006) suggests to use the capabilities of audio to increase
the emotionality of such informative sounds. For example, low health could
be indicated by a petrifying violin-solo.
The Acoustic Environment is the audio from the space that surrounds a
game. Outside noise has severe influences on how audio can be employed.
Noise from the environment can overlay audio from the game or deter the
player’s attention. Noisy surroundings are a big problem, especially in transportable games where the environment constantly changes. The game designer cannot know whether the surroundings of the game will be noisy or
quiet. Common causes include constantly changing amounts of people in a
shopping mall, events and festivals on certain days, talking tour guides in a
museum and so forth.
The general problem is that there are few ways of quenching external sound,
save for building a wall or using headphones. However, it is possible to influence certain acoustic parameters, to control the way that the player experiences the audio content. The design of space can deliver an enclosed surrounding for audio or at least engineer certain parts of the game space to enhance acoustics.
Sound waves are reflected or dimmed by objects inside a game space. Hard
and smooth surfaces tend to reflect more sound and amplify high frequencies,
making the environment seem loud and austere. Soft and malleable materials
like fabrics dampen sound and prevent echos, contributing to a warm and
comfortable emotional surrounding. The damping of volume, filtering of frequencies and reflections need to be considered by the architect of the game
space.
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The placement of speakers as well as the kind of speakers govern the acoustic
quality. The technology of speakers can also be the main aspect of an installation. At the Biennale 2004 in Venice in the parlor of Brazil, a large speaker the
center of attention. The user passes through a spacious room on a narrow
ledge, overhead there are two cement girders. To the user’s right, a large
speaker faces the floor at an inclination of about 30 degrees. The floor is
smooth and reflects the sound-waves emitted by the speaker in the direction
of the user. Thus, he hears the audio very clearly when he is near the focal
point of the reflection. Additionally, the two overhead girders reflect the sound
waves again, creating a hotspot where the sound waves appear to emanate
from within the user’s head.
Directional sound sources can focus sound waves in a certain direction or on a
certain location. This allows a game to deliver individual acoustic feedback to
players in a specific area of the game.
The noise in any given environment can be analyzed to adapt the audio output.
A game can adapt its volume and frequencies to be more audible. To achieve
this, the frequencies found in the surrounding noise can be used to regulate
the output frequencies. If, for instance, there are many voices in the surroundings, the mid-frequencies from about 350 to 800 Hz will be especially
noisy. The game can dynamically adjust an equalizer to boost the volume of
these mid-range frequencies to make its sound-content more audible.
However, the mid-frequencies should not be used too much by an augmented
reality game. Voices are most distinguishable in this frequency range and the
same is true for the player’s voices. In a social game where players need to
communicate, these frequencies should be kept free from other sounds. This
supports lively and unhindered communication between the players.
Booming sub-bass frequencies can be a powerful support for other feedback.
The lower a frequency, the more it is perceived as physical vibration or a tingling in the stomach. The increase in wavelength in low frequencies allows the
body to perceive individual vibrations. Due to the wavelength of sound, frequencies of about 82 Hz are generally felt in the area of the solar plexus.
Lower frequencies travel towards the stomach (Weber, 2006). However, many
people, especially children, are sensitive to bass. Therefore, the audience and
the surrounding environment have to be considered before employing this
kind of audio feedback.
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3.2.2.4.3. Haptic Feedback
Haptic feedback is perceived through physical contact. It includes force feedback in driving wheels and gamepads, along with vibrating motors used in
cell phones to inform the user of a call or text message. Similar motors can be
found in digitizers that have been refitted to simulate hard surfaces in thin air
(Figure 3.37). These 3D pens allow the user to touch virtual surfaces with the
pen (Spiegl, 2005). Another application are data gloves inlaid with motorized
resistors that can also simulate the touch of virtual surfaces in a physical way.
Figure 3.37: Digitizers are commonly used to trace sculptures into 3D models.
These 3D pens can be equipped with motors to give haptic feedback about the
surface of a virtual object.
Haptic feedback can usually be combined with haptic input devices. When the
player is focused on manipulating an object, he will also be perceptive of its
movement and haptic feedback. However, haptic feedback can also be applied
in combination with other input channels. For example, a touchscreen could
be outfitted with a surface that is soft to the touch. Additionally, a player who
sits in front of this soft touchscreen might get feedback from the chair he is
sitting on. The chair could vibrate when it is his turn to play, or warn him of a
dangerous situation.
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A sample application could employ a digital sculpting tool that acts both as a
haptic input and feedback device. The application lets the user model a
sculpture in thin air, using a pen, brush or wand. A wall-filling projection in
front of the user displays the sculpture. It can be made from different materials like clay, ice, lava, goo or marble. The user can switch between visual settings, in which his creation is placed, e.g. an ice sculpture in a snowy forest, a
wooden carving in a lively bazaar-hut on a hot, sunny day, or a stone statue in
a monumental Greek rotunda.
Maeda (2005) presented a prototype capable of delivering vestibular feedback,
causing spatial disturbance in the inner ear. Two sensors are attached to the
skin behind the ears and give out electric impulses that disturb the sense of
balance. The user will feel his head being tilted to one side and attempt to
counterbalance this feeling by leaning to the other side (Figure 3.38).
Figure 3.38: Vestibular feedback causes loss of balance which the player will try
to counteract. Amongst others, this can be applied in racing games.
This technology is applicable in many areas but also encourages applications
that center around this feedback device. For example, a balancing jester-on-arope game, a drinking-and-driving test simulator, an outer-space anti-gravity
simulation or a ‘mental’ Kung Fu fighting game that reacts to the opponent’s
brain-waves (Figure 3.39).
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Figure 3.39: Concept image for Brainball which uses selected brain-waves as
input from its players.
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4. The Design of Neon Racer
Chapter 4
The Design of Neon Racer
The following chapter analyzes the AR racing game Neon Racer in regard to
the design aspects outlined in the previous chapters. Aspects include the
emotional experience conveyed by the game, challenges and competition, details and incentives as well as hardware design, input and feedback channels.
Essential technical background information is given where it is relevant to understand game design decisions. The original technical descriptions can be
found in (Litzlbauer, 2006). The title of the game, Neon Racer, is not set in
italics to increase readability.
Considerable user feedback for Neon Racer is available from demos, conferences and festivals. Many of the player’s comments on the setup and software
are included in this chapter. User feedback makes it possible to determine
problems in playability and find ways of improving player-oriented game design in an augmented reality development environment.
4.1. Design of a Racing Game
4.1.1. Idea
Neon Racer is a multi-player racing game that adapts the simple and powerful
game-play of racing games to an AR tabletop setting. The game combines an
intuitive and tangible interface with quality content. A rich gaming experience
is created by using everyday, physical objects that act as collision obstacles
(Figure 4.1).
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The Design of Neon Racer
Neon Racer can be played by up to four players. The virtual world contains
their vehicles which are controlled with gamepads. Virtual vehicles collide
with real objects, allowing players to interact with both the physical and virtual world. The use of these two intuitive user interfaces, real objects and
gamepads, bridges the gap between virtual and physical interfaces.
Figure 4.1: Neon Racer is a multi-player racing game which includes the physical reality as part of the racecourse.
The game has simple rules and is easy to learn and very motivating, while
allowing each player to improve his skills and develop an individual racingstyle. The simple and cheery nature of the game appeals to a wide range of
cultures and ages. Neon Racer shows a possibility to boost social interaction in
open environments such as conferences, festivals, shopping malls or museums.
The game offers technological features which are both innovative and robust.
It has a compact hardware setup, uses custom image processing to detect collisions with real objects and uses state-of-the-art hardware shaders, executed
fully on the graphics card. In this way, Neon Racer is interesting as a research
project and also suitable for use as a permanent game exhibit.
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4.1.2. Goals and Rules
The rules of the game are simple and intuitive. Neon Racer does not require
more than basic knowledge of computer games. Real objects placed on the
course act as obstacles in the game. Virtual vehicles are steered by up to four
players who have to maneuver their vehicles through virtual checkpoints
(Figure 4.2). The aim of the game is to score as many points as possible by
crossing these checkpoints. A race ends when a time limit has been reached,
usually three minutes. Whoever has the most points at the end of a round is
the winner.
Figure 4.2: The player can gain points by crossing virtual checkpoints
and shooting opponents.
4.1.3. The Racing Game Genre
Racing games challenge the player to act and react quickly, predict motion and
collisions and to steer his vehicle clear of danger. Action and reaction is the
central element.
A simple racing game lets the player start quickly and careen around the racecourse with a feeling of having a “lead-foot”. This is the racing-game experience that players know from other racing games and will expect from any new
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game that labels itself as one. The core features of speedy interaction and
speedy races support the rules of the racing game like a frame enhancing, but
not occluding, a picture.
A racing game generally offers one single physical path that is ideally efficient
to get from start to finish. The player has to go around a lap in a way that is as
close to the ideal path as possible. Neon Racer loosens this restriction slightly,
because the player gains points whenever crossing one of three checkpoints.
The direction in which he drives is irrelevant. He could even bounce back and
forth between only two checkpoints.
Each player’s vehicle is mostly independent of the others, except for collisions
and torpedos. Every vehicle has its own health, score and gamepad to control
it. The only interdependency between vehicles is when they crash into each
other or try to navigate a narrow pass at the same time. The limited crossinfluences reduce the complexity of the internal computation.
In any game, the complexity of rules should be kept minimal, while offering
maximum freedom to the player. The possible paths that the player can take
through the game should be minimal. Each path requires design, programming, the creation of visual and audio content, testing and balancing. Further
work is necessitated by paths that influence each other. They might even require bug-fixing of all previously created paths, to ensure a stable and coherent gaming experience.
4.1.4. Setting
The setting of Neon Racer is a futuristic space race with cuddly powervehicles. The atmosphere needs to be supported by the on-screen visual style,
the sound design, but also the input devices used to control the vehicles. Everything has to contribute to the feeling of racing with future-generation spacevehicles.
In Neon Racer, the player should experience a feeling of cruising easily and
being detached from his current location and worries. The visual setting of
outer-space and the atmospheric, ever-changing music support the floating
sensation of veering about effortlessly (Figure 4.3).
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The Design of Neon Racer
Figure 4.3: The setting conveys a feeling of floating in space.
A setting of boats on a sea would have been similarly suitable to achieve this
effect. The swerving of the sea, the rhythmic beating of waves on the hull of a
ship, can also create an experience of floating and cruising. Alternatively,
Neon Racer could have been designed with the intention of creating a fastpaced, g-force, action-packed racing-game (Rollings, 2003). Visuals might then
have included futuristic, land-based mechanical hovercraft with huge afterburners, to create a sense of speed and acceleration.
4.1.5. The Player’s Impact on the Game
There are no long-term changes in Neon Racer. The game world is completely
reset after every round. A benefit of this is that the game is easy to balance.
There is no need to save, there are not complicated dynamics that prevent the
game from changing too much, etc. However, there is little room for developing the individuality of each player’s vehicle. The vehicles do not have individual strengths, acceleration speeds, slide resilience or other attributes. Every
player has the same prerequisites. This balances fairness but also reduces the
depth of the game.
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4.2. Visual and Audio Content
4.2.1. 2D Graphics
Neon Racer uses only 2D graphics to display the virtual content. The primary
reason lies in the way that participants view the game. They stand around the
table and look at the rear-projection screen. The angle of view is generally not
very steep, with the result that the screen appears distorted by perspective.
This is the case from every side of the table, so there are four main directions
from which participants can look at the game.
If 3D graphics were employed, the virtual camera used to display the graphics
on the screen would need to have a single position. Most likely, the virtual
camera would view the game from above. The 3D-depth information from the
top view would appear to every participant as distorted and incorrect, because their position differs from that of the virtual camera by at least 45 degrees. It is not possible to display 3D graphics correctly to every individual
without the use of personalized displays or tracking devices like HMDs.
To create an appealing visual style that every participant can enjoy, Neon
Racer employs 2D graphics. The smooth and chubby style suits the mode of
projection because pixel-blur and color-distortion can be ignored. The playful
and stimulating graphics also support the emotional experience of the player
(Figure 4.4).
Another advantage of 2D graphics is the direct control of shape, resolution
and color. The way that textures are painted in the graphics program is the
way they appear on the screen. To ensure complete accuracy of resolution and
color between the computer used for development and the projector used to
display the game, extensive tests were done. The projector image was analyzed to see how small details could be before they were blurred to invisibility
by the projector. Furthermore, the color space of the artist’s monitor was
matched to that of the projector. This ensured that the color shift between onscreen and in-game graphics was minimal. As soon as the in-game resolution
was defined, graphics were painted in a 1:1 aspect ratio. Consequently, the 2D
graphics on the development computer were very similar to the visuals of the
finished game.
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The Design of Neon Racer
Figure 4.4: The lively graphics of Neon Racer were built for the dark background and blur of a projector. They also enhance the emotional experience of
the game.
4.2.2. Incentives
Incentives allow the player to make the game more interesting, unpredictable
and versatile. Currently, Neon Racer offers bonus items, graphical treats and a
soundtrack that are shaped by the player. Additional features like different
background graphics and levels of difficulty, which are not yet part of Neon
Racer, may increase long-term motivation further.
4.2.2.1. Bonus Items
A common way to make a game more diverse are bonus items. They are tactical elements that the player can benefit from. Neon Racer offers several actionpacked extras such as photon torpedoes, exploding sheep, health-ups and
turbo-fields. These bonus items make the course of the race more unpredictable, because they allow each player to influence the game. Extras also invite
the player’s attention, while he also has to steer his vehicle with acumen.
Thus, the bonus items challenge the player while also adding to the complexity of the game.
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The Design of Neon Racer
Bonus items appear on the racecourse as small, circular images. A bonus item
can be collected by driving over it. It is then displayed on the vehicle’s power
sphere until it is used (Figure 4.5). An extra can be activated by pressing a
button on the gamepad. After its use, the extra disappears and the player has
to collect another item.
Figure 4.5: Any extra that has been picked up is displayed on the power-sphere
of the vehicle.
Bonus items are particularly interesting when they offer hidden or indirect
advantages. In Neon Racer for example, the turbo extra can be used to quickly
change direction when the vehicle veers off course or even to draw skid-marks
on the ground.
The other extras allow advanced players to engage opponents on a more tactical level. Sheep can be placed like mines on the racecourse. Placing them near
checkpoints makes it likely to hit nearby opponents. Torpedoes can be fired to
damage other vehicles. When a player’s vehicle is destroyed, he loses time
and the vehicle reappears after a few seconds. However, health-packs make
sure that there is always a surprise up someone else’s sleeve when things get
close.
When a player’s vehicles receives damaged, the amount is displayed on its
power-sphere. The sphere changes color from green to yellow to red and starts
blinking to indicate that the level of health is critical. Additionally, the damage
is visible on the vehicle’s chassis: Scratches, bumps, burns and torpedo holes
contribute to a run-down appearance.
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A current issue in Neon Racer is the balance of a player’s damage-dealing
capabilities and the amount he is healed when using a health-up extra. Sheep
and torpedoes do moderate amounts of damage while a health-up always
restores full power. Depending on the amount of available sheep and torpedoes, this system could work well. However, it is very hard to hit another
player’s vehicle with a torpedo. As a result, sheep are the main source of damage in the game, in addition to collisions between vehicles that also cause minor amounts of damage. The use of sheep, though, does not give the feeling of
having actively destroyed another player’s vehicle. Consequently, the degree
of competitiveness is reduced by the poor use of torpedoes. This also has its
advantages, because the players can concentrate more on racing and manipulating real obstacles than on shooting.
4.2.2.2. Motion Lines and Skid-Marks
Motion lines behind the moving vehicles enhance the feeling of speed for the
player. Moreover, the motion lines are also color coded to allow participants to
distinguish between the vehicles more easily.
Vehicles leave skid-marks on the ground whenever they use a speed-up item.
A skid-mark is a motion line that stays on the ground until the end of the current round (Figure 4.6).
Figure 4.6: Motion lines behind the vehicles and skid-marks. Whenever a
speed-up item is activated, vehicles leave skid-marks on the ground.
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The Design of Neon Racer
Skid-marks allow the player to give the racetrack a personal touch and
“draw” figures on the ground with their vehicles. At exhibitions, some players
even spent most of their time in the game collecting speed-up extras and decorating the racecourse.
4.2.3. Sound Design
As is common in computer games, the audio feedback of Neon Racer is made
up of sound effects and music.
Sound effects give immediate feedback to the player’s actions. Collisions with
real objects, torpedos fired, sheep placed on the racecourse and exploding vehicles all have individually designed sound effects that are recognizable and
unique.
The soundtrack is more than mere music that supports the game. The atmospheric soundtrack is created and influenced by the number of vehicles involved in the game and their speed. Each vehicle creates a part of the soundtrack as it moves. A vehicle’s track is loud when it drives quickly and almost
inaudible when it is standing still. This way, each player shapes the soundtrack while playing. Thus, the music constantly changes and varies its pitch
and tone. The sounds of all moving ships merge with a specially composed
background-beat to form an all-embracing composition (Figure 4.7).
Figure 4.7: Each vehicle makes up a clearly distinguishable part of the soundtrack as it moves. The ambient background beat (top row) is overlaid with each
vehicle’s track (2nd to 5th row) to form a dynamic composition.
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4.2.3.1. Limitations of Audio Feedback
The acoustic surroundings cannot be controlled with the setup space of Neon
Racer. This is the case in many AR installations that have to incorporate background noise into the game.
Audio is an important emotional channel that enhances the experience for the
player. However, in a non-controllable environment, the player might not hear
all the acoustic feedback from the game. Consequently, no information is conveyed only through sound that is not also displayed visually. All events in the
game such as explosions, the use of extras and collisions with real obstacles
are displayed and strengthened by acoustic feedback.
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4.3. The Setup Space
4.3.1. The Physical Dimension
4.3.1.1. Hardware Setup
A special table-based setup is used for Neon Racer. The table is similar to that
used in other interactive installations (Kruger, 1995; Ullmer, 1997; Leibe, 2000;
Starner, 2000; Levin, 2004). The compact setup offers enough space to accommodate a projector, a camera and a computer (Figure 4.8). The four-sided table
allows participants to gather around with a good view of the display. The
screen is a rear-projection glass-surface with a projector mounted inside the
table. This technology enables the virtual game to be displayed without any
occlusion caused by objects or players on the other side of the screen. To gain
enough distance for the projector to fill the screen, a mirror redirects the image. This also makes it possible to mount the projector horizontally which
helps to avoid overheating when the game runs for a long time.
Figure 4.8: The inside of the table contains a projector, a camera
and a computer to run Neon Racer.
The hardware table is an essential part of the game. It is the first thing that a
potential player sees and, thus, should immediately present the game as futuristic, cuddly racing-fun. The setup hides away the PC hardware which
would be immediately recognizable as belonging to a normal computer game.
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The table is a kind of black box that not only hides the technology from the
participants, but also lets them focus on the fantasy of the game. The fact that
the game works, although only a large black box is visible, gives a sense of
technological magic.
4.3.1.2. Area of the Game
The game space is limited to the surface of the table. Both the real and the
virtual world are limited to the projection screen. The setup is designed to
allow most players reach the entire table’s surface and, thus, manipulate any
real objects on it. This allows all players to interact on the entire area of the
game at any time. As a result, participants stay close to the table during a
game, however, physical movement is also restricted.
4.3.1.3. Relationship between Real and Virtual
Neon Racer takes place in a small virtual world that is entirely overseeable by
the player. He has a bird’s-eye view of the race and can observe everything
that happens in the game. Furthermore, the player autonomously commandeers his vehicle. When real objects are moved, he can attempt to steer past
them. When a bonus item appears, he can change his course to collect it, etc. In
combination, the player’s overview gives him the information he needs to
make meaningful decisions and his control allows him to effectuate them.
4.3.2. The Temporal Dimension
The temporal dimension in Neon Racer is similar to that of computer racing
games. Virtual time corresponds to real time and a race usually lasts three
minutes. There is a countdown that displays the duration of the current
round.
Timing is simple and suits the fast pace of a racing game. It is aimed at short
lap-times for quick, casual entertainment. However, due to other factors inherent in the game dynamics, Neon Racer can also be interesting for longer
play, especially when more players are involved who contribute to an intense
social experience.
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The Design of Neon Racer
4.3.3. The Social Dimension
Neon Racer aims at delivering a light-hearted entertainment experience for
both players and spectators. The game concentrates its efforts on casual entertainment. It is easy to learn both for experienced players and children, but
also for adults who are not familiar with computer games.
4.3.3.1. Number of Players and Participants
Neon Racer supports four active players, each of whom controls a virtual vehicle with the use of a gamepad. Both players and spectators can move objects
around the course, allowing them to contribute to the game. Thus, usually
passive bystanders can actively change the outcome of the race and even take
sides. In an exhibition, participants used coffee mugs and mobile phones to
play, even left packets of handkerchiefs and chocolate bars. Due to the involvement of its spectators, Neon Racer can be enjoyed by more than four
people simultaneously (Figure 4.9). It can even be played by a single person
competing only with spectators who manipulate the race course.
Figure 4.9: Neon Racer offers a social experience that involves both players and
spectators. Everyone can actively contribute to the game by moving objects.
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4.3.3.2. Competitiveness
Neon Racer pits all of its four players against each other. They compete to gain
the most points within the given time-limit. Players can exploit real objects,
bonus items and the vehicle’s driving capabilities to gain an advantage. The
game is balanced to encourage use of all available options. A good driver can
be interrupted by real objects, just as a poor driver can gain points if he times
the use of bonus items well. In the end, only a cunning combination can make
a player stand out from the rest. However, Neon Racer is not too competitive
and fast-paced act as a platform for unburdened social communication.
The spectators are an unpredictable element that makes every game unique.
They can choose to help a certain player, make life harder on him or challenge
all participants alike. They can utilize all sorts of objects, be it fluffy toys, coffee mugs, business cards or snacks. Round objects can even be rolled around
the table and some objects are deformable like fabrics, a foldable yardstick or a
pliable eraser.
4.3.3.3. Private and Public Space
All physical and virtual space in Neon Racer is shared by the participants. The
objects on the table can be moved at any time by anyone. Virtual information
displayed on the screen is visible to everyone nearby.
A kind of private space is offered through the gamepads. They allow individual control of a vehicle that is totally exclusive to a single player. He can challenge his driving and show off his individual skill. The vehicle’s unique visual
style also make them more individual and add to the player’s feeling of controlling a personal space.
4.3.3.4. Social Interaction
The game fosters a casual social surrounding, ideal to meet people, engage in
leisurely conversation and create contacts. Participants can communicate with
others while slowly learning about the game. They can start by watching a
game, move objects to interact as spectators and ultimately take control of one
of the vehicles.
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The player’s freedom to start or leave at any time is respected by the game.
The player can stay for one round or race for a longer time, switch back to
moving objects around without controlling a vehicle, etc. However, in the current version, new players cannot join an ongoing round but have to wait until
the current race is over. It should be possible for everyone to start playing at
any time.
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4.4. Input and Feedback
4.4.1. Control of the Vehicles with Gamepads
Each player controls one vehicle with a gamepad. He can steer, accelerate and
reverse to navigate around the racetrack and avoid physical obstacles. Vehicles
can collect bonus items by driving over them and the player can employ these
extras using a button on the gamepad.
A current drawback of the gamepads is their complicated and featureless design. There are more buttons than are necessary for the game and their effect is
unclear (Figure 4.10). The interaction could be improved by using simple or
even especially designed gamepads with an intuitive button-layout. At exhibitions, players not used to gamepads found it difficult to learn how to control
their vehicles.
Figure 4.10: The design of the gamepads that are currently used in Neon Racer
is complicated and ambiguous. This makes the meaning of buttons unclear.
4.4.2. Interaction with Real Objects
In Neon Racer, ships bounce off physical objects. This requires the game to
recognize any physical object placed on the table and deliver this information
to the virtual part of the game.
4.4.2.1. Tracking
Every object casts a shadow onto the table’s surface. This shadow can be used
to detect the location and shape of any non-transparent object. A camera is
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The Design of Neon Racer
used to detect the objects which is situated inside the table. It records the table’s translucent surface from below.
The game’s virtual content, however, is also displayed on the table’s surface. A
normal camera would record the shadows and the projected image as well.
This would lead to recognition of both real and virtual objects on the table.
Both would be interpreted as obstacles, because the camera cannot differentiate between the projected image and real shadows. To avoid this, Neon Racer
uses an infrared filter to avoid the camera image being polluted by the projected image. The light from the visible spectrum does not pass through the
filter and the projected image becomes invisible (Figure 4.11).
Figure 4.11: An infrared image from the camera inside the table. The projected
virtual images are invisible in the infrared spectrum.
The use of infrared has another advantage when the environment is too dark
for the camera, real objects cannot be accurately tracked. However, infrared
spotlights can be mounted above the table to provide additional light that is
invisible to the human eye. As a result, Neon Racer can also be played in very
dark surroundings, while the projector makes sure that the game’s virtual
content is always visible.
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Collisions between virtual vehicles and physical objects are the core principle
of Neon Racer. To detect physical objects, the grayscale camera image containing the object’s shadows is sent to the obstacle detection system. First, a
binary image is created, using an adjustable threshold. Then, a contour following filter is applied to detect the pixel borders of the objects on the table.
The pixel borders cannot be used for collision detection due to performance
issues. To accelerate collision detection, the objects’ pixel borders are approximated by lines.
The detected outlines of objects are displayed in the game to give feedback to
the player. Thin, dark-red lines are used to visualize the borders. These are
clearly visible but not obtrusive. Whenever a participant moves and object, the
lines give instant feedback that the game has successfully registered the obstacle’s new position. A further benefit of this is that participants can experiment
with different objects and even with their hands and arms, to see if they can
stop or even trap a player’s vehicle (Figure 4.12).
Figure 4.12: Virtual red lines are displayed around the edges of physical objects
to give immediate visual feedback to the participants.
4.4.2.2. Game Engine and Obstacle Detection System
A modular interface allows the game engine to communicate with the separate obstacle detection system. The obstacle detection recognizes the physical
objects on top of the table. During development, the modular interface allowed for autonomous implementation of the two systems.
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The separation of engine and obstacle detection system has another advantage. The graphics are drawn on the graphics card, while the obstacle detection runs on the CPU. This frees enough resources of the CPU to allow for
proper execution of the extensive obstacle detection system.
Stability and robustness were important goals during development. This is
crucial for any AR game that is presented at public spaces and has to run for a
longer period of time. In prior exhibitions, the game has run smoothly for a
long time without any noticeable drawbacks.
4.4.3. Physics
An important aspect of the game is the physically correct behavior of the vehicles. Collisions between vehicles and the real obstacles have to seem authentic.
When two objects collide, a realistic bouncing behavior is simulated.
To facilitate the detection of collisions, each virtual object in the game is represented as a circle. For instance, the vehicles have a shield protecting them, extras are circular, checkpoints are round, etc. Most entities in the game are designed to be round. This reduces the efforts of detecting a collision, but also
fits the cuddly graphical style of the game.
Neon Racer takes place in space, thus, the vehicles navigate a frictionless
space. In the setting of the game, there is no aerodynamic resistance. Hence,
they ought to have lazy flight characteristics and veer easily in curves. However, the current implementation of the game makes such extreme usage of
this freedom that the vehicles are very difficult to control. They slide in the
slightest curves and are generally hard to steer, with the effect that the vehicles
mostly bounce off of real obstacles and each other.
Interestingly, the bouncy behavior leads some players to build a network of
real objects that reflect their vehicles around the course. Objects can be placed
on the table in such a way that ships, driving into an obstacle at the right angle, bounce off in the direction of the next checkpoint. There, another bounceobject can be positioned. Skillful players can use this tactic to quickly bounce
their vehicle around the course, gaining and edge over their opponents.
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However, the controls are so challenging that many players spend most of
their time trying to increase their skills to steer the vehicles, instead of using
their energy to move around real objects on the table. Sadly, this defies the intention of Neon Racer to a certain degree. Most players spend a lot of time
with the game and enjoy themselves, but they do not interact with the real
world enough. By improving the physical model, the pace of Neon Racer can
be improved by making the vehicles faster and easier to control.
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4.5. Conclusion
Neon Racer offers important features for entertainment installations such as
technical robustness, a player-oriented interface and engaging game-play. The
game focuses on light-hearted casual entertainment in a social surrounding.
Players compete in a virtual setting, while communicating with real people
(Figure 4.13).
Figure 4.13: Neon Racer is a social casual-game which combines virtual and
physical input to create an entertaining experience.
Neon Racer uses a novel approach for controlling the game by incorporating
both physical and digital interaction. It allows players to interact on multiple
levels: Players steer the vehicles with traditional gamepads, while each participant and spectator can use real objects to influence the race. This combines
a widely familiar computer-game control with an intuitive physical interface.
Both direct physical contact and gamepad participation are necessary to be
successful. Neon Racer enhances not only the classical racing game, but creates a setup which allows for direct physical interaction with the game world.
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The technical setup is an all-in-one table which is fairly easy to configure
without major adjustments. The technology of the game is conveniently built
into the table, with the effect that users more openly engage the game without
focusing on the technical setup.
Through the use of infrared-based image processing, Neon Racer is employable in different lighting conditions, i.e. locations can be both bright or dark.
The game setup is flexible and can be placed in bars, exhibitions, shopping
malls and many others.
Neon Racer was demonstrated successfully at the Pixelspaces Exhibition, part
of the Ars Electronica Festival in Linz, at ISMAR 2005 and at the Europrix
Multimedia Top Talent awards in Vienna. People of all ages enjoyed the game.
Most were amazed that real objects were integrated into the game. When
someone started to move objects around, it triggered the other players and
spectators to join in. Judging by the consistently positive feedback of the audience, Neon Racer appears to have bridged a gap between entertainment and
technological research.
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4.6. Team and Acknowledgments
Neon Racer was developed at the Upper Austria University of Applied Sciences Hagenberg for Digital Media in 2005. The object detection and image
processing were developed by Manuela Waldner. The game engine and controls were programmed by Wolfgang Litzlbauer. Ines Stuppacher was responsible for implementing the hardware shaders that create particle effects such
as motion lines and skid-marks. Doris Bernert was in charge of including
gamepad controls and programming the sound output. Markus Weilguny was
mainly responsible for game design and the creation of visuals. The process of
game design was a joint effort of the entire team. Everyone involved constantly gave feedback, brought in new ideas and worked to improve both
technical features and playability.
In addition to the team at university, Mandala Weber of Circled Cube composed and produced the sound effects and interactive background tracks.
Thomas Weilguny supplied additional graphics for the racetrack.
Neon Racer could not have been as successful as it has been, without the support of the technical coaches Peter Brandl and Jürgen Zauner, along with Michael Haller who made it possible for Neon Racer to be presented at the Ars
Electronica Futurelab. There, Neon Racer seems to have received the attention
of Horst Hörtner who greatly helped by supplying the hardware for the first
table-based setup and inviting Neon Racer to be part of the Ars Electronica
Festival 2005. Ever since, Neon Racer has been very successful and hopes are
high for the production of further player-oriented augmented games.
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5. Conclusion
Conclusion
Augmented games let players share a physical and virtual space. The social
experience of board games or athletic games can be enjoyed by players. Additionally, augmented games harness novel interaction technologies to create
immersive, absorbing and enjoyable games. These factors can be utilized to
enhance purely virtual computer games. A new generation of player-oriented
games could be forged.
5.1. Current Chances for Augmented Games
Casual games might currently be the biggest chance for AR games. They are
easy to learn and appeal directly to a broad audience. AR interfaces can reach
people who are unfamiliar with mouse and keyboard, PC operating systems
or the internet (Stapleton, 2005). Grandpa and grandson might play together
in an augmented maze or by manipulating giant playing cards. AR games are
more pervasive than computer games and can be set up at public locations,
e.g. in shopping malls, at an office’s recreation-room or in restaurants, bars
and discotheques. Many public locations are already equipped with cameras,
projectors or other devices that can be employed in games. Airports have security cameras and monitors, skyscrapers are illuminated with commercials
by large-scale projections. Yet, no airport has equipped one of its cameras with
an EyeToy, no one has attempted to play an AR James Bond game on a wall of
the Houses of Parliament in London to rival Christo’s enshroudings or other
event-art. Augmented games can reach numerous locations by choosing from
a broad range of spaces, players and input and feedback channels.
Casual games are also easier to develop within the usual workflow of AR
prototyping. Most prototypes illustrate new software or technological findings.
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Conclusion
During development, the time available for game design and content-creation
is often limited. Casual games require less graphical and audio-content than
fully featured games, they are easier to balance and the design of the game
and the hardware is generally less complex.
The core of casual games is a single, simple idea that is refined into an enjoyable game. Limiting the design to refine a single idea seems feasible, in regard
to the research aspect of most AR prototypes. A simple idea like throwing a
real ball to hit a virtual target or driving around in circles with virtual vehicles
on a real table, as is the case in Neon Racer, can make for an enjoyable game.
5.2. Developing Game Concepts
New game concepts for augmented reality can be developed for existing
hardware or derived from existing games of other genres. Additionally, completely new game ideas can be used to drive the development of new technology.
Existing technology can be the basis of building a game. The design can be
structured around the input and feedback channels that should be employed,
as well as around the space. Feedback can rely mainly on visuals, audio or
physical feedback. The choice depends on the hardware that ought be be used.
The important thing is that the game is fun and that the emotional experience
of the game suits the technology.
In AR, multiple input and feedback channels can be used. Information can
pass through displays, speakers, HMDs, lights, moveable objects and many
more. This allows extremely complex interaction such as allowing players in
different locations to interact with the same object simultaneously or letting
them steer and shoot from a tank together. In AR, it is especially tempting to
make games complicated, because of the endless possibilities. No matter how
complex the technology may be, the interaction always has to be clear, concise
and coherent. The amount of information that the player can absorb does not
increase with more feedback channels. On the contrary, augmented games are
even more sensitive to bad design than computer games. The interaction has
to be even clearer than on a computer screen. The player of a computer game
only has to concentrate on a screen and audio feedback that depends on his
136
Conclusion
speakers. In AR, the player’s surroundings can address multiple sensual levels
and the player will not always be able to overlook the entire game space.
A good starting point when drafting an idea is the use of one input channel
and one feedback channel. For instance, a game uses physical, full-body input
that is strenuous, along with feedback based on audio. The dimensions of
space define the physical, temporal, social and emotional setting. For example,
the game is played on an outside space, approximately ten by ten meters. This
gives room for six to twelve players, grouped into teams of three to four players each. Due to the physical movement, a match lasts no longer than ten minutes. The game should foster casual, athletic play that involves all participants, no matter whether they are in good or bad physical condition. Players
are visually focused on their teammates and have to listen to cues from the
game. Most of the game takes place in the real world.
To structure an idea into a game, it has to be refined according to game design
aspects. What expectations do the players bring to the game? How can these
expectations be described to form attainable goals? What rules can be employed to allow the players to reach the goals according to their wishes? What
challenges does the game introduce to spur the players on in their endeavor to
reach the goals?
In the aforementioned example, the aim for the three members of a team is to
form a triangle and encircle one single other player. Whenever the constellation of players changes and a team manages to encircle a single person, a point
is awarded. Teammates have to be aware of their positions and play together
as a whole. They will plan, shout, think, stop, whisper and try to outwit the
other teams. When more than a single person is encircled, no points are given.
Thus, teams cannot move too far outward from the center of the game area.
This allows slower players to sidestep others and gain points for their team.
The positions of all players constantly changes and keeps players engaged
physically and mentally.
The initial idea needs to be refined, reworked or perhaps completely redone to
form a finished game. The rough outline in the example still lacks detailed
rules, incentives, unpredictable challenges, additional rewards and more
complex tactics. Also, the way that the audio feedback is given when points
are awarded has to be clear and understandable. Especially players from
137
Conclusion
teams that did not gain a point will want to understand the decision of the
game.
Another way to generate ideas is to transport a game to an AR setting or to
combine two games. As mentioned before, it is not trivial to transport a game
into AR. Computer games such as Lemmings, Dyna Blaster, Dungeon Keeper and
others could be made into AR games. Off-screen games like Halma, Mikado,
Hearts and Hammer-Throw might also be appropriate. However, the interaction
has to be adapted to suit the possibilities of an augmented space. This is often
more challenging than creating new games all-together.
Two or more games that are completely unrelated can also be combined to
come up with ideas for AR prototypes. Imagine Snakes and Ladders paired with
Quake, Civilization combined with Creatures.
Augmented games allow for even more room in game design than any virtual
or real genre by itself. The possibilities are endless and the future may hold
even more.
5.3. Technology and Emotion:
Ideals of Future Games?
Every new generation of technological devices has taken a similar path in
evolving its games. PC games were the first widely available virtual gaming
platforms. Their development spans over the last 30 years and has given rise
to numerous genres. Arcades also started off with simple games long ago.
They evolved into smaller, cheaper home-entertainment consoles that also
started off with Jump and Run games and gradually offered adventures and
more complex genres. Recently, mobile phones have turned from mere telephones into small computers. They, too, are starting off with the kinds of casual games that were available for the PC years ago. However, their development is much faster and mimics those of computer games. Augmented Reality
has also started off to explore the gaming sector and is now in the early stages
of experimenting with casual entertainment. AR can reach the level of PC
games and expand even further: into reality. In the decades to come, there is
no way of telling where AR games might go.
138
Conclusion
New kinds of games often evolve from the availability of new technology. This
is true for computer games which make use of improving graphics-quality
and real-time capabilities and it is also true for AR games. Nowadays, AR
games employ a new technology mostly to create simple games. Often, these
only scratch the surface of the potential of the technology, because the development of a new interface-technology accounts for more than the development of a great game. With the rapid innovations in interface-technology,
there are currently more interfaces than games. In contrast, computer games
have evolved over the last decades and were fostered only by mouse and keyboard. Considering this comparably plain and ambiguous interface, the results
are astonishing. Augmented games might go even further, when they harness
current technology to create more meaningful games.
With the advent of AR technology making its way into the games industry, the
question arises whether they might already drive the evolution of computer
games further. Computer games have been focusing mostly on fun and lighthearted entertainment, sporting new technological features and hardware
requirements as features for the user. These two directions, technology and
fun, might be overrated.
Game developers have to ask themselves if fun and entertainment are really
the only emotions that can be associated with a computer game. In other artforms such as literature, music and film, even in sports, we experience a broad
range of emotion that is not present in its entirety in computer games. Crawford (1982), for example, mentions that an intense drama with a sad ending
can cause pathos; in an exciting sports competition we can feel euphoria or
pity; participating in a play can be enthralling; intense physical training lets us
experience exertion and satisfaction. These activities are experienced with the
entire body and mind, with total concentration and focus. As a Nintendo
spokesperson put it: “It’s about the heat of emotion, not the chill of technology” (Surette, 2006).
Another question is the role of technological features in determining the quality of a game. The newest technical features and hardware are without value
in a game that is not playable. Playability gives depth and meaning to a game.
It can be found in a game which is well balanced and leaves a lot of room for
the player to imagine his own world and bring this fantasy to life. The player
should not be confronted with long load-times that are caused by anachronistic graphics, etc.
139
Conclusion
Satoru Iwata of Nintendo says that there are many people who no longer play
games, because of the increase in technological complexity and decrease in
playability. He argues that ex-gamers might be brought back to games, along
with non-gamers who have never played on a computer, by “reinventing”
games, i.e. by employing new interface devices and ideas (Surette, 2006). AR
technology is predestined to follow this trend and develop a new way of
playing.
Augmented reality games are still evolving and the vast possibilities of the
medium make it almost impossible to offer strict guidelines for development.
New technologies and old genres clash to form prototypes for the next generation of entertainment. It is an important step in developing a unique AR
gaming experience to understand the player’s expectations and the emotional
implications of employing new interface technologies.
The game designer makes decisions that shape the experience of players, the
competition between them and the involvement of spectators. He can choose
cameras over gamepads, screens over HMDs or haptic over physical input. A
game may address public or private spaces like busses or private homes, let
players be static or moving, be set up as fixed installations or use mobile
PDAs, interact on a virtual or physical level by manipulating a touchscreen or
by throwing balls.
Augmented games can convey more social warmth and physical reality than a
computer game ever could. Imagine the potential of a new generation of
games that combines the variety of computer games with the social and
physical possibilities of children’s games, board games and sports. Players can
take on the roles of ghost hunters who roam the streets of a real city, on the
lookout for virtual spooks. They can role-play an elf with augmented sight
and an acute sense of hearing delivered by AR feedback devices. They can be
Sherlock Holmes, tracing the tracks of virtual crimes long past and do so in
their own neighborhood. Whatever the future may hold, augmented games
are full of potential. In the words of Chris Crawford (1982): “Games are puerile, but see them for what they could be.”
140
Appendix
Contents of the DVD
File System: DVD Single Layer
Mode: Single Session
Master Thesis
Path: /
design aspects weilguny.pdf
design aspects weilguny.pages
Master Thesis (PDF file)
Master Thesis (source file)
Additional Material
Path: /
images/
documents/
Images used in this thesis
Bibliography (PDF and html files)
141
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