Practical Techniques for Implementing Emergent Gameplay

Practical Techniques for Implementing Emergent Gameplay(Would the Real Emergent Gameplay Please Stand Up?)

[email protected]@ionstorm.com

Practical Techniques Practical Techniques for Implementing for Implementing

Emergent GameplayEmergent Gameplay

Would the Real EmergentWould the Real EmergentGameplay Please Stand Up?Gameplay Please Stand Up?

Randy [email protected]

Harvey [email protected]

mailto:[email protected]



IntroIntro• 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



Our TopicOur 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



FocusFocus

• 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



DisclaimersDisclaimers

• Emergent gameplay isn't necessary to design good games

• No holy wars, despite the provocative title of the presentation



TakeawayTakeaway

• 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?



OutlineOutline• 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



I – Intro to EmergenceI – Intro to Emergence

• Definitions

• Vocabulary

• Examples



A Typical Real-World A Typical Real-World DefinitionDefinition

• 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 real-world emergence



Global WarmingGlobal Warming



MDA FrameworkMDA Framework

• A rules-oriented approach to game design

• Mechanics—The rules of the game

• Dynamics—Real-time rules interactions

• Aesthetics—Human emotional responses



Emergence in Video GamesEmergence in Video Games(our definition)(our definition)

• A second order game Dynamic created by the interaction of first order game Mechanics.



Example 01: GTA3Example 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



Example 01: GTA3Example 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



Example 02: Tactical Example 02: Tactical ShooterShooter

• 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



Example 03: ThiefExample 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



MDA FrameworkMDA Framework



MDA Applied to MDA Applied to EmergenceEmergence

• 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



II – Creating EmergenceII – Creating Emergence

Quantitative

• Mechanics

• Connecting Mechanics Together

• Relevant Technology

• Populating the world with Mechanics



Where Mechanics “Live”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.



more aboutmore about Autonomous AgentsAutonomous 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



Creating Emergence by Creating Emergence by Adding Indirect ConnectionsAdding 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



Creating Emergence by Creating Emergence by Adding Indirect ConnectionsAdding 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



The Tactical Shooter The Tactical Shooter ExampleExample

• 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



Visualizing All MechanicsVisualizing All Mechanics



-1 Mechanic-1 Mechanic



-2 Mechanics-2 Mechanics



Getting Mechanics to Getting Mechanics to ConnectConnect

• 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



Example from DX:IW:Example from DX:IW:Choosing Where to InvestChoosing 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



Player ImprovisationPlayer 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



Player ImprovisationPlayer Improvisation



Invest in Related Invest in Related MechanicsMechanics

• 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



Supporting TechnologySupporting Technology

• Takeaways» Some technology supports the

implementation of emergence better than others

» Need to work with technologists to evaluate your technology status



Supporting TechnologySupporting Technology• Explicitly hard-coded Mechanics are

messy and difficult to support

• You might forget to implement one of them



Supporting TechnologySupporting Technology• The Stimulus System is a generalized

way for objects to listen to each other

• You can describe objects intuitively



Supporting TechnologySupporting Technology• Easier to create and modify connected

Mechanics

• More reliable and likely to create improvisational emergence



Ion Storm’s Supporting Ion Storm’s Supporting TechnologyTechnology

• 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”



Populating the world with Populating the world with MechanicsMechanics

• 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?



Examples of World Examples of World Population from ThiefPopulation 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



Examples of World Examples of World Population from ThiefPopulation 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?



III – Qualifying EmergenceIII – Qualifying Emergence

Qualitative

• Aesthetic Goals

• Meaningful Emergence

• Involving the Player



What are your Aesthetic What are your Aesthetic Goals? 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)



Meaningful EmergenceMeaningful 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



How involved is the How involved is the player?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.



Robot Factory GameRobot Factory Game



Player Perception of Player Perception of Emergent ExperiencesEmergent 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



Player Perception of Player Perception of Emergent ExperiencesEmergent 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



IV – Wrapping UpIV – Wrapping Up

• Design Process

• References



Emergent Gameplay Design Emergent Gameplay Design ProcessProcess• 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



ReferencesReferences• 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 Practical Techniques for Implementing for Implementing

Emergent GameplayEmergent Gameplay

Randy [email protected]

om

Harvey [email protected]

Q & AQ & A

Practical Techniques for Implementing Emergent Gameplay

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