5) Half Life rocked my world, it was the first FPS game I'd played that actually had a good story line. Couple that with fantastic graphics and a excellent difficulty curve and you get Half Life. Still, IMHO, the best one-player FPS.
4) On the good old Amiga 500+, Dune II was genre defining. Build your tanks, roll them in, kill everything (as long as you chose Harkonnen). 'Nuff said.
3) Perhaps part of the reason I put Bloody Roar II (for the PSX) in my list is because I am 2001 British Champion at it

However it's a top fighting game which makes Tekken look simplistic. A proper fighters game where winning actually took skill rather than random button mashing (60+ combo's can be done by entering each move in individually) and blocking was much more than holding 'Away'. Top, top game.
2) For top multi player fun, I have to cop out and say Counter Strike. It's simple, amazingly simple, you just do the same thing over and over again, but God, is it fun.
1) Very unoriginally, Final Fantasy VII is still my favourite game of all time. It was almost perfect in every way, and had so many hidden bits and sub games that it lasts forever. FF8 had better graphics and nine was nearly as good, but FF7 still remains, for me and many other people, the best game ever created.