Paper: A Survey on the Need and Use of AI in Game Agents

Sule Yildirim and Sindre Berg Stene. 2008. A survey on the need and use of AI in game agents. In Proceedings of the 2008 Spring simulation multiconference (SpringSim '08). Society for Computer Simulation International, San Diego, CA, USA, 124-131.

This paper is a good survey on the use of various AI methodologies in commercial video games. They found that the most commonly used AI methodologies to achieve game AI can be stated as follows:

* Decision trees: can be realized by If-Then statements..

* Fine state machines

* Command hierarchies

* Manager task assignment

* Path finding (A*)

* Terrain analysis

* Influence mapping

* Formations

* Flocking

* Emergent behaviour

* Artificial Neural Networks 

* Genetic Algorithms

* Fuzzy logic

One of the most interesting AI approches listed above is emergrnt behavior. This kind of AI has been explored in Black & White.

Also, they present a misture of needed AI depending of the type of game. For example, In RPG games, a team is built up to reach a common goal. The intelligence required from a team or from individual characters depends on how complex it is to reach to the common goal.