ummm!, first you need to know whats possible and what you would need to do to get certain effects, plus the AI for a FPS is totaly different from the AI for a puzzle game or Chess for example, so first you need to decide exactly what game you are making, for example in a FPS what the terrain will be like, paths and walkways in a built up area or structure, or natural with lakes etc, then you need to decide on either paths or waypoints, pathfinding or random paths etc to get to the player if you are planning to attack him, then how much cpu time you can spare to make the soldier "smart", ie does he take cover to reload, throw grenades, use cover or just rush you, try to get health packs if hit? etc.
How smart the NPC is will be up to your ingenuity and the amount of cpu time you have to spare when the rest of the game is running, best bet is to get some idea of the problem by reading up on AI in general and experimenting with a block on a matrix for a start, even the most top end games have to make sacrifices, for example the lack of collision in RTCW when soldiers die, and the tendency to drop objects unreachably inside walls etc when they do (plus the obvious hack that repositions them into reachable locations some of the time), or the flaw that makes them try to run to somewhere when they are in a corner and trying to run through a wall, if ID have problems with AI then you won`t be alone if you struggle to get something that works well, in fact you will be in with some very good company
cheers.
Mentor.
PC1: P4 hyperthreading 3ghz, 1gig mem, 2x160gig hd`s, ATI radeon 9800 pro gfx, 6 way surround sound, PC2: AMD 1.2ghz, 512mb ram, FX5200 ultra gfx, stereo 16 bit soundblaster, ups.
