Practical Techniques
for Implementing
Emergent Gameplay
Would the Real Emergent
Gameplay Please Stand Up?
Randy Smith
Harvey Smith
[email protected]
[email protected]
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
[email protected]
[email protected]
Intro
• Harvey Smith—Deus Ex/Invisible War
• Randy Smith—Thief 1/2/3
• Ion Storm aesthetic goals
» Improvisational (player-authored) gameplay
» Benefits from large gameplay possibility space
» Emergence provides more explorable space
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Our Topic
• How to Add Meaningful Emergence
to Video Games
• Topics that have been covered
elsewhere:
»
»
»
»
History of Emergence
Emergence and Narrative
Emergence and Uncertainty
Benefits and Costs/Risks of Emergence
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Focus
• Less Theoretical, More Practical
» Related to modern game system design
» Skewed toward large-scale action games
• Emergence within a game system
context
» No player psychology, social influence, etc.
» Focus on the system space of game
– Power-ups, Weapons, Tools, Monsters
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Disclaimers
• Emergent gameplay isn't necessary
to design good games
• No holy wars, despite the
provocative title of the presentation
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Takeaway
• A practical approach to creating
meaningful emergence in your own
game designs.
• You are a game designer
» You design game systems
» You want to focus on emergent gameplay
» How do you accomplish this?
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
[email protected]
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Outline
• Preamble
• Intro to Emergence
• Creating Emergence
– Creating Mechanics that result in emergent
game dynamics
• Qualifying Emergence
– Creating emergent gameplay that results in
meaningful game aesthetics
• Wrapping Up
•Q&A
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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I – Intro to Emergence
• Definitions
• Vocabulary
• Examples
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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A Typical Real-World Definition
• A discernable, higher-level behavior
of a system which is not
immediately obvious by looking at
the low-level rules that govern the
system’s behavior.
• …let’s look at an example of realworld emergence
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Global Warming
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Global Warming
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
[email protected]
[email protected]
Global Warming
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
[email protected]
[email protected]
Global Warming
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
[email protected]
[email protected]
Global Warming
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
[email protected]
[email protected]
MDA Framework
• A rules-oriented approach to game design
• Mechanics—The rules of the game
• Dynamics—Real-time rules interactions
• Aesthetics—Human emotional responses
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Emergence in Video Games
(our definition)
• A second order game Dynamic
created by the interaction of first
order game Mechanics.
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Example 01: GTA3
• Player accidentally flips his car, which
explodes, injuring nearby pedestrians
who begin to attack him
»
»
»
»
»
Player takes a jump 
Car flips and lands upside down 
Car explodes 
Nearby pedestrians are injured by explosion 
Pedestrians begin to attack player
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Example 01: GTA3
• Player accidentally flips his car,
which explodes, injuring nearby
pedestrians who begin to attack him
»
»
»
»
Player takes a jump 
Car flips and lands upside down 
Car explodes 
Nearby pedestrians are injured by
explosion 
» Pedestrians begin to attack player
• Note that there is no explicit
Mechanic describing this behavior
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Example 02: Tactical Shooter
• Indirectly Connected game Mechanics
»
»
»
»
»
Gas barrels Leak poison when ruptured
Poison Kills enemies and players
Bullets Kill enemies, and Rupture gas barrels
Weapons Fire bullets when dropped
Enemies Fire bullets, and Drop weapons on death
• Player shoots guard  guard drops gun
 gun goes off when it hits the ground
 bullets rupture barrel  poison leaks
out  poison kills other enemies
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Example 03: Thief
• In order to injure a nearby guard, player
ignites an oil puddle by knocking a candle
off a table
»
»
»
»
»
»
Player throws a box at a table 
Table wobbles 
Candle falls off table 
Candle falls into oil puddle 
Oil puddle ignites 
Nearby guard is injured by the flames
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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MDA Framework
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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MDA Applied to Emergence
• Mechanics
» The rules of the game
» You modify Mechanics to alter emergent
interactions
• Dynamics
» Real-time interactions between Mechanics
» Mechanics connecting to each other
» Where emergence happens
• Aesthetics
» Human emotional responses
» Wider exploration space, emergent narrative
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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II – Creating Emergence
Quantitative
• Mechanics
• Connecting Mechanics Together
• Relevant Technology
• Populating the world with Mechanics
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Where Mechanics “Live”
• Power-ups
» “When guns hit the ground, they fire off bullets”
• Environmental Objects
» “When barrels are damaged, they release poison
gas”
• Simulations
» “Cars can flip upside down when they land from
jumps”
• Autonomous Agents
» “If pedestrians take damage, they attack whoever
is responsible”
• Etc.
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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more about
Autonomous Agents
 Can act independently, possibly react
dynamically to situations
 Guard AIs in Deus Ex and Thief
 Cars and Pedestrians in GTA3
 The Bat in Adventure
 Special properties
 Emergence without direct player intervention
 Make the world feel alive
 Create dynamic situations
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
[email protected]
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Creating Emergence by Adding
Indirect Connections
• Emergence fails to happen when
Mechanics aren’t indirectly
connected
• Emergence can be created by
adding more indirect connections –
making the Mechanics “listen to”
each other
» Guard with torch slips on oil puddle 
» Guard falls to the ground
» Nothing else happens
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
[email protected]
[email protected]
Creating Emergence by Adding
Indirect Connections
• Emergence fails to happen when
Mechanics aren’t connected
• Emergence can be created by adding
more connections – making the
Mechanics “listen to” each other
»
»
»
»
Guard with torch slips on oil puddle 
Guard falls to the ground 
Guard drops torch 
Torch ignites oil puddle
• …let’s talk more about connecting
Mechanics
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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The Tactical Shooter Example
• Indirectly Connected Game Mechanics
»
»
»
»
»
Gas barrels leak poison when ruptured
Poison kills enemies
Bullets Kill enemies, and Rupture gas barrels
Weapons Fire bullets when dropped
Enemies Fire bullets, and Drop weapons on death
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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[email protected]
Visualizing All Mechanics
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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-1 Mechanic
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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-2 Mechanics
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Getting Mechanics to Connect
• Again, it helps to have a rules oriented approach
• It’s tempting to spam the world with Mechanics,
to pile them on
• Mechanics are independent, but indirectly
connected
• Some Mechanics are more highly connected
• How do you get the best return on your
investment?
• Choose Mechanics that have relationships to
each other
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Example from DX:IW:
Choosing Where to Invest
• Prismatic Resonator Biomod
» Fewer Indirect Connections
– Beam Triggers (3 types)
• Bot Domination Biomod
» More Indirect Connections
– All robots (8 types), Cameras, Turrets, Spiderbombs
» Bots are improvisationally useful for combat, door
opening, setting traps, etc
– Players started using spiderbombs to open doors
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Player Improvisation
• Players ‘Unlocked’ Doors with Spiderbombs
• Indirectly Connected Game Mechanics
» Spiderbombs
– Spawn Spiderbots
» Spiderbots
– Obey All Bot Rules
• Susceptible to Bot Domination
• Susceptible to EMP
• Explode If Damaged Post-EMP
» Bot Domination
– Possess Bots
– EMP Bots Post-Ejection
» Doors
– Can Be Locked/Lockpicked
– Destroyed By Explosions
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Player Improvisation
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Invest in Related Mechanics
• If you’ve already got these Mechanics:
» Flamethrower can catch enemies on fire
» Burning enemies can catch furniture on fire
• Add more elements and Mechanics having to do
with fire, e.g.:
»
»
»
»
»
Fire extinguishers
Oil puddles
Dynamite
Candles
Water arrows
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
[email protected]
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Supporting Technology
• Takeaways
» Some technology supports the
implementation of emergence better
than others
» Need to work with technologists to
evaluate your technology status
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Supporting Technology
• Explicitly hard-coded Mechanics are messy
and difficult to support
• You might forget to implement one of them
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Supporting Technology
• The Stimulus System is a generalized way for
objects to listen to each other
• You can describe objects intuitively
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Supporting Technology
• Easier to create and modify connected
Mechanics
• More reliable and likely to create
improvisational emergence
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Ion Storm’s Supporting
Technology
• Stimulus System
» Generalized channel for objects to listen to
each other
» Don’t have to explicitly hard-code Mechanics
• Property System & Object Hierarchy
» Quick and easy creation and editing of objects
• Scripting System
» Quick and easy to describe resulting behaviors
» Oil puddle: “When I receive fire stim, turn into a
fire puddle”
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Populating the world with
Mechanics
• For Mechanics to connect, they
typically have to exist in physical
proximity to each other.
» How rich is your world with Mechanics?
E.g. – how many gas barrels exist in your
world?
» How often are the connected Mechanics in
proximity to each other? E.g. – do you
ever place guards near gas barrels?
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Examples of World Population
from Thief
• Negative example
» Fire elementals that re-light torches when guards
are nearby in Thief
» Good idea, but Fire elementals and Guards /
Torches were never in the same levels
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Examples of World Population
from Thief
• Positive example
» Player shoots arrow at a candle to knock it
over  arrow misses and hits metal door
instead  nearby guard hears sound and
comes to investigate
» Physical surface, Sound Propagation, and
Lighting house Mechanics in Thief
» ..and they populate the world
exhaustively.
» What elements already exist in your world
which you can add Mechanics to?
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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III – Qualifying Emergence
Qualitative
• Aesthetic Goals
• Meaningful Emergence
• Involving the Player
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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What are your Aesthetic Goals?
• What do you hope for emergence to
contribute to your game?
» Deus Ex = Empower many emergent
solutions
» Thief = Creating the occasional sublimely
tense moment of emergent challenge
» GTA3 = Simulate a dynamic, responsive,
living world; Enable emergent mayhem
» All three = Authoring your own
experience (emergent narrative)
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Meaningful Emergence
• In accordance with aesthetic goals
• The player perceives the events
• Impact on gameplay experience, Not
just some wacky outcome
» No gameplay relevance: Prox mine wall
climbing
» Gameplay relevance: Spider bomb door
unlocking
• Meaningful to the fantasy
» Violates fantasy: Age of Empires sheep
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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How involved is the player?
• Does the player have input into the Mechanics
which create emergence?
• Theoretical Game: There is a factory with lots of
robots interacting emergently. If they touch
you, you die, but they don’t react. Get to the
other side.
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Robot Factory Game
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Player Perception of Emergent
Experiences
• Reactive – does not require player input
» “Emergent challenge” – a challenging situation that
develops emergently
» E.g. – the previous robot factory example
» E.g. – pedestrians in GTA3 turn hostile toward the
player
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
[email protected]
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Player Perception of Emergent
Experiences
• Proactive – player must provide
input
» “Emergent solution” or “Emergent
strategy” – the player creates their own
solution to a problem by leveraging their
understanding of the game’s emergence
» E.g. – igniting oil puddles by knocking a
candle off a table in Thief
» E.g. – player runs over pedestrian to
summon ambulance for ambulance
missions in GTA3
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
[email protected]
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IV – Wrapping Up
• Design Process
• References
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
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Emergent Gameplay Design Process
• Aesthetic Goals
» Widening possibility space via emergent systems
• Technology Considerations
• Plan Game Systems
» Player agent(s), tools, traps, resources, etc.
» Decide where to invest, Disregard low connection Mechanics
• Populate world with Mechanics
• Evaluate system Dynamics
» Quantitatively
– Litmus test—2nd order consequence?
– Common enough?
– Perceptible?
» Qualitatively
– Dynamics match the fantasy?
– Did you meet your aesthetic goals?
• Iterate
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
[email protected]
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References
• Various References to Emergence
» Marc LeBlanc’s GDC Lectures
• Rules of Play
» Book by Eric Zimmerman and Katie Salen
• Dynamics for Designers
» Will Wright’s 2003 GDC Lecture
• Complexification
» Book by John L. Casti
• Emergence
» Book by Steven Johnson
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
[email protected]
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Q&A
Practical Techniques
for Implementing
Emergent Gameplay
Harvey Smith
[email protected]
Practical Techniques for Implementing Emergent Gameplay
(Would the Real Emergent Gameplay Please Stand Up?)
Randy Smith
[email protected]
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