Three States and a Plan: The A.I. of F.E.A.R.
Jeff Orkin · 2006
If the audience of GDC was polled to list the most common A.I. techniques applied to games, undoubtedly the top two answers would be A* and Finite State Machines (FSMs). Nearly every game that exhibits any A.I. at all uses some form of an FSM to control character behavior, and A* to plan paths. F.E.A.R. uses these techniques too, but in unconventional ways. The FSM for characters in F.E.A.R. has only three states, and we use A* to plan sequences of actions as well as to plan paths. This paper focuses on applying planning in practice, using F.E.A.R. as a case study. The emphasis is demonstrating how the planning system improved the process of developing character behaviors for F.E.A.R.