Now you see it - Now you don’t
Intro to Game AI
Book Learnin’
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University of Chicago
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BA in General Studies
Masters work in AI & Information Systems
Northwestern University
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PhD work in AI: Robotics & Video Games
Street Smarts
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Game Design and Tuning Workshop
Indie Game Jam/Experimental Gameplay
Workshop
IGDA Education Committee
... and kickin’ it with developers, in general
What is AI?
Some terms
AI is...
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a philosophy
an abstraction
a tool
Philosophy
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People do things based on rough goals and
sketchy plans – modifying their behavior
when problems or opportunities arise.
Abstraction
Tool: Finite State Machine
start
end
Tool: Planner
state
goal
Tool: Agents
What is Game AI?
Some Context
Environment
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Big projects, getting bigger
Dynamic worlds/systems
Time is still an issue
Problems
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Pathfinding
Sensing
Reacting
Expressing
People
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Programmers
Designers
Players
Goals: Programmers
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Intelligent, coherent, reactive behavior
Consistent, accurate sensing
Goals: Designers
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Extensible, flexible code
Intuitive interface
Goals: Players
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Coherent
Believable
Entertaining!
Fortress of Solitude: “If they worked properly,
they’d be tools - not toys”
Currently
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Slow progress on
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sensing
reacting
Problems crop up in
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code
interface
State of the Art
Game AI Today
State of Game AI?
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“State machines and hierarchical AIs. The
simple rules-based finite- and fuzzy-state
machines (FSMs and FuSMs) continue to be
the tools of choice for developers,
overshadowing more "academic"
technologies such as neural networks and
genetic algorithms.” – Woodcock 2001
Finite State Machines
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Systems, Sub-systems and Sub-Sub
systems
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Proliferation of nodes = slower code
Changes in Agent design = chaos
Schizophrenic behavior = common
Difficult to debug
Rule-Based Systems
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Special Cases made easy
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Scripting can be tedious
Debugging can be difficult
Flexibility? Extensibility?
Hierarchical AI
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Commanders, Middlemen, Drones
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Lots of reasoning
Lots of inter-level communication
What does the user see?
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Best in strategy contexts?
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Other approaches?
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Black and White, Creatures, The Sims
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Neural Net
Learning/Reinforcement
Transparency? (why?)
Transitions? (how?)
Other approaches?
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Thief I & II
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Complex Sensing
Brooksian, Distributed AI
Scalability? (how many brains?)
Intuitiveness? (which brain?)
More Recently
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Optimizations
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Blackboard Systems (NOLF 2)
Broadening scope
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Diagnostics (DX 2)
Expressive Characters (HL 2)
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Paul Eckman
Recent Issues
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New systems and genres introduce new
problems...
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Dynamic Path Planning
Strategic Team-based AI
Massively-Multiplayer AI
Next-Generation AI?
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Will new technology engender new and
improved techniques?
Will new problems have clear, simple
solutions?
What about Middleware?
Game AI In a Box?
Middleware
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Animation &
Locomotion Control
Middleware
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Behavior Control Systems
Middleware
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Structural Organization/Interface
Middleware
Middleware
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Hard to get developers to use it
Not clear what value it provides
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are they the right abstractions?
will the tools be flexible enough?
AI seems specific to game genre/content
Looking Forward
Juicy AI Problems
Dynamic Game Adjustment
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Difficulty
Pacing
Story
Characters
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The future looks... complicated!
Natural Language Generation
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Context-aware conversations
Common-sense responses
Dynamic phrase generation
Expressive Characters
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Memory
Feelings
Independent goals
Persistence
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Character Changes, World Changes
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Chess Examples
Persistence
“There are no character classes in Project Ego, only personality
styles that evolve according to the decisions you make. Your
character will age as time progresses, and the actions you take
put an idiosyncratic spin on his or her appearance. Early
wounds will show up later as scars. Lethargy will manifest as a
little extra blubber around your middle, and anaerobic exercise
will show up in the form of Olympian muscles.
Even more important than your looks, your reputation will
depend on the kind of life you lead. The incredible freedom of
gameplay allows you to pursue every occupation from dashing
hero to indolent bum to mischievous cutpurse.”
How would you build “Fable”?
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Persistent beliefs about the main character
Clear presentation of change/progress
Characters that remember events
Gossip?
Grudges?
Wrapping up
What we covered...
Game AI Then
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Big talk up to about 2001
Plenty of proposed ideas tanked/ignored
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Republic
Black & White
Game AI Now
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Gamasutra/Game Developer
AI Programming Wisdom
Game AI Tomorrow
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Look to next round of games for ideas?
AI ‘04 – workshop in the works
GDC ’04 – hopefully some tidbits
Contact
[email protected]