Fundamentals of
nd
Game Design, 2 Edition
by Ernest Adams
Chapter 20: Artificial Life and Puzzle Games
Objectives
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Know the different forms of artificial life
games and simulations
Design basic artificial life systems
Know the steps to designing puzzle games
Understand the player’s needs for puzzle
games
© 2009 by Pearson Education, Inc
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Artificial Life Games
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Artificial life is a branch of computer science
research
A-life involves modeling biological processes
A-life is the study of emergent properties—
unanticipated qualities or behaviors that arise
out of the interactions of complex systems
A-life games typically focus on maintaining
and growing a manageable population of
organisms
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Artificial Life Games (Cont.)
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Artificial pets
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They can be simulations or fantasy pets
Almost always cute; seldom reproduce or die
Gameplay concentrates on training, maintenance,
and watching the creatures
Pet needs a lot of AI
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Variety of triggers and behaviors
Show the pet's emotions through behavior
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Artificial Life Games (Cont.)
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Artificial pets (cont.)
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Player influences pet's emotions through
interaction
Pet should interact meaningfully with other pets
Pet must be able to learn
Rich AI distinguishes artificial pets from other Alife
Artificial pet is a software toy—no victory condition
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Artificial Life Games (Cont.)
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The Sims
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Player controls the sims physically and indirectly
affects their relationships
Each sim has a personality
Cross between an artificial pet and a CMS—game
has an economy
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Artificial Life Games (Cont.)
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The Sims (cont.)
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Needs
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Each sim has six needs that must be met
Needs drive the sims' behavior
Need-based AI is the heart of most simple behavior
simulations
Skills
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Sims (in the first edition) have six skills they can improve
Sims teach themselves skills
Time management is critical
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Artificial Life Games (Cont.)
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The Sims (cont.)
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Personalities
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Game tries to simulate relationships among individuals
Variables define each sim's personality and how they
react to each other
Success of The Sims is based on the
unprecedented scope for creativity it offers and its
emphasis on interpersonal relationships
© 2009 by Pearson Education, Inc
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Artificial Life Games (Cont.)
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Defining affinity between two characters:
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The “I Can’t Stand” Rule – A character cannot
stand another character who has an attribute
above a certain threshold
“Birds of a Feather” Rule – Characters with high
levels of one attribute are attracted to others with
a high level of the same attribute
“Opposite Attract” Rule – Characters with high
levels of one attribute are attracted to others with
a low value for the same attribute
© 2009 by Pearson Education, Inc
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Artificial Life Games (Cont.)
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God games
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Characteristics
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Player is a god with limited powers who gets more
power from simulated worshippers
Omnipresent interaction model and an aerial perspective
They often share qualities with CMS (indirect control of
population) and real-time strategy (compete directly
against a rival god) games
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Artificial Life Games (Cont.)
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God games (cont.)
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The economy of god games
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Player’s power (mana) grows with the number and
prosperity of his worshippers
Size of the population influences the maximum amount
of mana the player may have and the rate at which
mana is restored when it is below maximum
Positive feedback can be limited in various ways:
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People do not reproduce instantaneously
Making land suitable for population growth costs mana
Mana cost of using higher-level powers rises exponentially
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Artificial Life Games (Cont.)
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God games (cont.)
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Gameplay in god games
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Primary challenge is to produce population growth
He must also damage the other god’s worshippers and
repair the damage the rival god does to the player’s
people
To design a god game, start with the question of
what powers you would like the god to have
A god game needs a lot of interesting animations
for the people
© 2009 by Pearson Education, Inc
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Artificial Life Games (Cont.)
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Genetic A-life games
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Characteristics
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They are about managing a population over time
Player tries to achieve goals for the whole population
Can’t concentrate too much on individuals
Designing a genome
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Genome defines the creatures’ inheritable
characteristics such as eye color, hair color, height, etc.
Alleles are traits inherited from each parent
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If parents have different traits, usually one wins—brown
eye allele dominates blue eye allele
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Artificial Life Games (Cont.)
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Genetic A-life games (cont.)
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Mutation
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Change to the gene caused by an environmental factor
Mutations may benefit the population by introducing
random new values into the gene pool
Life span, maturity, and natural selection
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Each creature needs a natural life span
To evolve through natural selection, creatures must have
a time of immaturity before they can reproduce
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Genetic mutations that cause death in children do not get
passed on because children do not reproduce
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Artificial Life Games (Cont.)
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Genetic A-life games (cont.)
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What does the player do?
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Create new individuals and add them to the population
to see how their genes influence the population
Add and remove environmental hazards that would
weed out certain genes
Play with the rate and nature of mutation by adding or
modifying mutagenic objects or areas of the
environment
Mate individuals to select for particular characteristics
© 2009 by Pearson Education, Inc
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Puzzle Games
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Characteristics
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In puzzle games, puzzle solving is the primary
activity
Puzzle games usually provide related challenges,
variations on a theme
The types of puzzles offered include pattern
recognition, logic, or understanding a process
The puzzles give the player clues that have to be
solved to meet the victory condition
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Puzzle Games (Cont.)
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Scott Kim’s eight steps in puzzle game
design
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Find inspiration
Simplify
Create a construction
set
Define the rules
© 2009 by Pearson Education, Inc
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Construct the puzzles
Test
Devise a sequence
Pay attention to
presentation
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Puzzle Games (Cont.)
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What computers bring to puzzles
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Enable nonphysical or awkward moves
Include computation features
Enforce the rules
Record player moves and undo them
Structure the experience
Teach
Use bells and whistles
Enable online play
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Puzzle Games (Cont.)
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Checking the victory condition
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Path to the solution might be different than you
planned
Check the solution, not the way it was reached
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Summary
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You should now understand
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How to identify an artificial life game and
simulation
How to design basic artificial life systems
How to describe the steps to designing puzzle
games
How to explain the player’s needs for puzzle
games
© 2009 by Pearson Education, Inc
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