By Brian Bell Evolution of Artificial Intelligence In Video Games
What is Artificial Intelligence? • The term Artificial Intelligence (AI) was coined by John McCarthy in 1956 • As a Noun • The Intelligence of Machines. • As a Field • “The science and engineering of making intelligent machines.”
How does AI apply to games? Game AI is game design, implemented.
Overview • Step through the History of Video Games • Highlight certain AI techniques and trends • Go over some of the pitfalls of modern AI development in the Video Game Industry
Pong • One of the First Video Games • Manufactured by Atari • Released in 1972 • Designed for 1 or 2 players. • Essentially just table tennis in 2 dimensions.
The AI of Pong • There is Logic to how the Computer moves the paddle. • The computer predicts where the ball with end up based on a number of factors then moves the paddle to that predicted location. • To simulate Human error the computer is designed to skip its adjustment every 8 frames.
Pac-Man • Developed by Namco • Distributed by Midway (in US) • Released: 1980 • Single player only • Simple maze game
Ghosts • While the Ghosts appear to move in a random order this is not always the case. As each Ghost has its own Algorithm to control its actions. Chases Pac-Man Try to get in front of Pac-Man Moves at Random*
Super Mario Bros. • Developed by Nintendo • Released in 1985 • Classic example of the Platformer
Scripted AI • Enemy units in the game are designed to follow a scripted pattern. • Either move back and forth in a given location or attack a player if nearby • Became a staple technique for AI design.
Sim City • Developed by Maxis • Published by Electronic Arts • Released in 1989 • First in a series of Simulation Games which are often at the forefront of AI technology
A Living World • The player is able to manipulate certain aspects of the city. • The population of the City acts somewhat autonomously. • Furthermore the game will simulate random disasters.
The Sims • Developed by Maxis • Published by Electronic Arts • Released in 2000 • A life simulation game in which the player has control over a semi-autonomous people.
Complex characters • The Sims characters can be manipulated by the player but will also carry out day to day tasks on their own. • Characters also have defined needs and personality traits that dictate how they act in given situations.
Complex Object Interactions • Characters are able to interact with an arrangement of objects in the environment due to unique object logic.
Black and White • Developed by Lionhead Studios • Published by EA games • Released in 2001 • Simulation game in which you play God.
Black and White • Similar to Sim City • You had more control over the environment and the people in the game • You could also create armies and wage war
AI Learning • You could control and train large creatures • You could then punish or reward the creatures based on how they complete tasks. • Over time the creatures will learn how you wish tasks to be done based on how they are treated.
Combat Oriented Games • Simulation games are more advanced • Combat Oriented Games are more Popular • Evolution of AI in combat games has advanced quite a bit in the past 10 years.
Halo: Combat Evolved • Developed by Bungi • Published by Microsoft • Released in 2001 • First person shooter that garnered fame for competently brining the genre to Consoles
Dynamic Enemy AI • Enemies reacted in dynamic ways. • Different enemies would react differently in different situations. • Enemies would work together against the player.
Tasks Condition Action • Conditional Nodes represent read only functions. • These functions are when the AI unit observes some information about its environment • Examples: Searching for enemies or nearby cover, determining orientation. • Actions Represent actual performed functions. • These functions are generally reflected in the graphical representation. • Examples: Firing on an enemy, throwing a grenade, reloading, ducking behind cover.
Sequences and Selectors ? Sequences Selectors • A sequence represents a group of tasks that must be carried out in order for the overall task to complete • A selector will ultimately only carry out one task but attempt to run each of its child task until it finds the correct task for the situation. 1 2 3 1 2 3
Behavior Tree ? Investigate Patrol Attack ? ? ?
Behavior Trees:Good and Bad Benefits Costs • Allows AI units to act in dynamic ways depending on the situation • Allows designers to group different actions together for different situations • Allows for enemy differentiation • Can be time consuming to generate • More complex actions require more complex trees • Running through all the possible actions can take a lot of time.
Behavior TreesBottom Line • Are a good way to provide dynamic actions to individual AI Units • Generally require a larger AI control structure for proper implementation.
Left 4 Dead • Developed and published by Valve • Released in 2008 • A co-op first person shooter set in a zombie apocalypse.
AI Director • The game utilizes an AI director that will change the game based on how well the player(s) are doing. • This can make the game more or less difficult for players with different skill levels. • This also changes the events of the game between different play sessions.
The Elder Scrolls V: Skyrim • Developed and Published by Bethesda Game Studios • Released in 2011 • Open World RPG set in a fantasy world
Unbalanced AI • Non Playable characters (NPCs) and enemies within the game world react dynamically with the player and each other.
Unbalanced AI • Enemies are not designed to deal with simple obstacles
Problems With AI in Gaming • There are a number of issues that prevent Video Games from being the best area for the evolution of AI • Despite the how far AI in games has come over time no game is perfect. • There are a number of reasons as to why this is and will always be the case.
Release Schedule • Time • The game has to be released at some point and not everything that needs to be addressed can be addressed. • Money • Games are expensive to make so items are generally prioritized to put the most effort into what is considered most important.
Is it fun? • Games are about Entertainment • While the AI in a game might be very advanced it might not necessarily be entertaining.
Are Video Games good for AI Development? The Good The Bad • AI is essential to Games • Games provide a simulated world where programmers can experiment • The Game Industry is the largest area where AI is being applied. • Time and Money are an issue • Innovation might not be that important • Entertainment is more important then quality
References • Champandard, A. (2008, December 28). Behavior Trees for Next-Gen AI. Retrieved May 2011, from AiGameDev.com: http://aigamedev.com/insider/presentation/behavior-trees/ • Champandard, A. J. (2012, February 9). Trends and Highlights in Game AI for 2011. Retrieved May 2012, from aigamedev.com: http://aigamedev.com/insider/discussion/2011-trends-highlights/ • History of Game AI. (n.d.). Retrieved May 2012, from AI Game Programers Guild: http://gameai.com • Montfort, N., & Bogost, I. (2009). Racing the Beam: The Atari Video Computer System. The MIT Press. • Wexler, J. (2002). Artificial Intelligence in Games: A look at the smarts behind Lionhead Studio’s “Black and White” and where it can and will go in the future. Rochester, NY: University of Rochester.