artificial intelligence in video games jason fuller 1

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Artificial Intelligence in Video GamesJason Fuller

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What is Game AI? Imitate intelligence in the actions of non-player

characters (NPCs). Make the game “feel” real. Obey laws of the game Show decision making

and planning

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Goals of Game AI Be fun! Be challenging but not

overwhelming (unless the hardest difficulty is selected)

Make sure the AI does not cheat! (At least do not get caught)

AI often get bonuses when difficulty increases

Do not hog all the resources! (CPU time)

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Types of Games

1. Action games Shooters (FPS and Third-Person) Racing, Sports

2. RPG games (Role Playing Game) Often include many

action game aspects of AI

3. RTS games (Real Time Strategy)

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Game AI Types Action and RPG AI tend to work better with Finite State

Machine based AI RTS AI used Finite State Machines in the early years of AI

development. RTS AI work best with Artificial Neural Networks and Fuzzy

Logic Both contain path finding components

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AI Path Finding

Dijkstra’s Algorithm

A* Algorithm Most commonly used Finds the shortest path The world or map of the game is represented by a grid of points

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A* Algorithm Allows for high optimization

Either by changing the search algorithm to better suit the game or by changing the data structures.

Very similar to how people move between locations in a city.

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Finite State Machines (FSM) Simplest and most basic AI model. Consists of:

States

State Transitions

Most common for Action games! Not many different actions for NPCs

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Finite State Machines Among the States and State Transitions there are 4

components: States which define behavior

State transitions which are the movement from one state to another

Conditions which must be met for state transition

Events/Actions which are internally or externallygenerated which may lead to a state transition

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FSM Example

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FSM Disadvantages Very predictable Too many states get tough to organize Since there are such crisp rules between states, NPC does not

feel natural

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FSM within a State States have a FSM within them

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Modern FSM Example

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History of Finite State Machines In 1952, the game Nim used AI to play against an opponent. 1960’s & 1970’s Spacewar!

Pong

Space Invaders

1980’s Simcity

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History Continued1990’s Dragon Quest IV

Warcraft

Half-Life

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Artificial Neural Networks (ANN) No agreed definition, most common one is “a network of

simple processing elements, which can exhibit complex global behavior, determined by the connections between the processing elements and element parameters.”

Mathematical model inspired by biological neural networks. An adaptive structure that can learn.

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ANN Structure Very similar to the structure of our brain.

Input layer, processing (hidden) layer, output layer

Learns by example

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ANN Structure The hidden layer is not just a straight line of nodes Each node in the hidden layer will contain just a small part of

the overall calculation The nodes have connections

between each other withcertain weights

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ANN Structure The weight of the connections between the nodes determine the outcomes

of the calculations

If a node is triggered by 2 different nodes it can then determine which one is more important

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ANN Learning

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Black & White Came out in 2001 First to effectively use

Artificial Neural Networks

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Halo Wars Came out in 2009 Featured a “Custom” difficulty level that used Artificial Neural

Networks

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Fuzzy Logic Introduced in 1965 for use in Artificial Intelligence research Present problems to computers in a way similar to how humans

solve problems and that everything is a matter of degree (or preference or context).

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Example Problem

A store owner needs to decide how much produce to order.

Elements to take in to consideration: Time of year? What is the weather like? Is there a Holiday coming up?

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Video Fuzzy Logic: An Introduction

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Games

Now that the major types of AI have been covered, I will go into more detail about what games they are used in.

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Racing Game AI Large-scale cheating! AI already know the track and optimal path AI already has complete behavior determined before the start

of the race

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Racing AI graphs

General Path

Optimal Path

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Racing Game AI In its basic form, it is the most basic of game AI but in some of

the racing simulators, the AI are more complicated If the player is using the optimal path, the AI will actively try to

push them off of it. The AI will also use tricks such as spinning out opponents by

making their back tires lose grip.

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FPS Game AI Implemented with a layered structure Bottom layers control the path finding tasks and animation

selection Higher layers control the tactical reasoning which is where the

Finite State Machine would be.

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A* Graph of FPS or RPG World

Unplayable Zone

Playable ZoneGeneral path

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FPS Continued F.E.A.R. series has revolutionary AI AIs have knowledge of map elements and will flank the player AI will break through walls and windows to get to the player AI will rush when they heavily outnumber the player

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RPG Game AIMany encounters with AI are unscriptedGTA IV and Far Cry 2 made great leaps in “friendly” AI

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Elder Scrolls IV: Oblivion Released in 2006 During testing, a story important NPC kept being found dead. A mechanic of the AI was the cause.

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Bioshock Infinite The player companion, Elizabeth (who is an AI), is almost

entirely unscripted.

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RTS Game AI Started out using Finite State Machines to control AI Too many options to cover AI was “dumb” AI would build up in a strict way Once the player found a strategy that worked against the AI, it

would always work. RTS AI switched to a combination of Fuzzy Logic and Artificial

Neural Networks

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RTS Game AI By changing to Fuzzy Logic and Artificial Neural Networks (ANN):

Fuzzy Logic led to smarter responses to attacks

ANN led to smarter development of base and better long term decisions

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A* Graph of RTS Map

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RTS Continued Maxis is again changing the simulation landscape with the new

Simcity Every “Sim” is a full AI

Have there own agenda

Have specific wantsand needs

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Video SimCity: Economics AI

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Future of Game AI Game AI have made great leaps forward since they were first

developed. An AI that can learn how you play a game would be a great

opponent

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References Champandard, Alex. "Top 10 Most Influential AI Games." Aigamedev.com. N.p., 12 Sept.

2007. Web. 25 Feb. 2013. <http://aigamedev.com/open/review/top-ai-games/>.

Grant, Eugene, and Rex Lardner. "The Talk of the Town." TheNewYorker.com. The New Yorker, 02 Aug. 1952. Web. 25 Feb. 2013. <http://www.newyorker.com/archive/1952/08/02/1952_08_02_018_TNY_CARDS_000236053>.

Grzyb, Janusz. "Artificial Intelligence in Games." - CodeProject. Software Developer's Journal, n.d. Web. 25 Feb. 2013. <http://www.codeproject.com/Articles/14840/Artificial-Intelligence-in-Games>.

"Neural Networks: A Requirement for Intelligent Systems." N.p., 2007. Web. 25 Feb. 2013. <http://www.learnartificialneuralnetworks.com/#training>.

"Short Term Decision Making with Fuzzy Logic And Long Term Decision Making with Neural Networks In Real-Time Strategy Games." Hevi.info. N.p., n.d. Web. 25 Feb. 2013. <http://www.hevi.info/tag/artificial-intelligence-in-real-time-strategy-games/>.

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Videos Fuzzy Logic

http://www.youtube.com/watch?feature=player_detailpage&v=P8wY6mi1vV8#t=117s

SimCity

http://www.youtube.com/watch?feature=player_detailpage&list=UUnje_8ilXP7KB2vdssyAWug&v=MxTcm1YFKcU#t=37s

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QUESTIONS?