Evolving AI Opponents in a First-Person-Shooter Video Game

Abstract

One of the major commercial applications of AI is in the rapidly expanding computer game industry. Virtually every game sold today has some sort of AI, from the "computer player " in a chess game to the machine-gun-toting enemies in a first-person shooter (FPS). Any virtual being that does not behave in a strictly pre-scripted manner has some sort of AI behind it. Sadly, however, the multi-billion dollar gaming industry has done very little to advance the field of AI. The industry has moved past the day when an AI opponent would not even react to the death of his teammate standing three feet away, but that does not mean these bots, as they are commonly called, have any serious thought processes. Cube 1 is an open-source FPS, written in C++ for Linux and Windows, that is based on a very unorthodox engine that emphasizes simple 3D designs to provide a quickly and cleanly rendered environment. The Cube Engine is, to quote its website, mostly targeted at reaching feature richness through simplicity of structure and brute force, rather than finely tuned complexity. The code for Cube is much shorter and simpler than that for many other FPS games, and, because it is open-source, we have full access to all of the code and thus almost any change is possible. We realized that given the simplicity of Cube, developing a straight hard-coded AI that would show real improvement would be a difficult project. Rather than spending lots of time trying to figure out how the agents (bots, monsters, opponents) should behave, 1