its a big industry.. two of my mates are doing computer games programming at uni. the design side of it is completely separate from the programming side; i'm assuming you're into the design side?
the programming side (for decent games anyway), require all sorts of physics and stuff, and if I understand all this correctly, you write an "engine" for the physics and stuff. and then there's all the AI programming etc... it gets pretty complex. thats about all i know about this stuff, heh