Tetris.
To be fair, it's the only computer game I've ever played, but I do like it a lot.
Virtua cop 1, 2, on one of the big arcade screens.
Syndicate Amiga
Sensible Soccer Amiga
Cannon Fodder Amiga
ISS N64
Syphon Filter PS1
all GTA games I've played
The Warriors PS2
Xenon 2 megablast Amiga
Speedball 2 Amiga
North and South PC
Rick Dangerous PC and Amiga
G-Police PS 1 (might be G-police 2 I forget, a bit of a syndicate ripoff but still pretty good)
Tekken 3
Age of Empires 2
Shogun: Total War
Tetris
Zelda on SNES (and on NES)

Half-Life (1 and 2)
GTA (but espesh the first few)
Syndicate Wars

Goldeneye n64
Silicona Valley - n64
Command & Conquer - red alert 1

Ultima Online (oh baby)

Random japenese football games on old pre-NES era consoles.
Actually i still have a snes at my mums house, must check if it works sometime.
Hearts of Iron 2
http://forum.paradoxplaza.com/forum/forumdisplay.php?f=255
Streets of Rage (dunno if one or two is better. at least Skate's on two) and Golden Axe are musts. That cartridge with those two and Shinobi is probably one of the best things ever. Bomberman. NBA Jam. Super Mario (not even gonna try picking which is best). Sonic (same applies).
The GTA games are the only ones from modern consoles I'd consider to be best. And, oh man, the best by FAR. Actually Fifa and Pro Evo are up there too, but other than that I'll stick with the SNES and Mega Drive.
PC :-
Alpha Centauri
Hearts of Iron II
Galactic Civilisations II
Wizardry VIII
The Baldur's Gate Series (esp. II!)
Planescape: Torment
The Sims / Sims II
Playstation:-
Tekken Series
Alien vs Predator: Extinction
C64
Pirates!
Gunship
Red Storm Rising
Pool of Radiance
Wizball
EDIT: How could I forget ELITE for the C64 - the hours of my life I lost to that game! And its sucessors on the PC X2 and X3!
Streets of Rage (dunno if one or two is better. at least Skate's on two) and Golden Axe are musts. That cartridge with those two and Shinobi is probably one of the best things ever. Bomberman. NBA Jam. Super Mario (not even gonna try picking which is best). Sonic (same applies).The GTA games are the only ones from modern consoles I'd consider to be best. And, oh man, the best by FAR. Actually Fifa and Pro Evo are up there too, but other than that I'll stick with the SNES and Mega Drive.
Yeah NBA Jam was fuckin class and Bomberman. Goldenb Axe arcade was great.
I can't believe no-one else has said Shadow Dancer - that shit was amazing, it was Shinobi with a fuckin big wolf-dog.
I damn myself - I have 3 days to submit my differentiation draft and I'm on here trying to get Hooded Gunman to work, jesus.
It's shite, if you leave it alone for more than an hour or two during the day you will get turned over. I think there's a flaw in the defence mechanics.
I don't know anything about video games but this is fucking awesome
Frontier Elite. Difficult, but that game had depth that I only ever read about.
Quake 3. Fantastic playability for me. Really felt as if i was in the game.
Probably a sim. I'm sure i learnt alot from say, Civ II (which used to be quite popular. Abot te pyramids and shit); Settlers had cool animations that still make me a little reminiscent.
I'll admit, once I passed my mid teens I lost interest in video games so most of my favourites are late 80s/early 90s NES, SNES and coin-ops (back when kids could actually afford them), and a a few magedrive games
Streetfighter 2 (snes and arcade)
Final Fight (arcade, snes one was a bit crap)
Double Dragon - 1,2 and even 3 (arcade and nes)
Mario bros 1-3 (nes)
Super Mario world and Mario kart (snes)
Goldeneye (n64)
Streets of rage (arcade)
Shinobi and Shadow Dancer (arcade)
ISS (snes)
KungFu Master (arcade)
Probotector/Contra (arcade, nes and snes versions)
PitFighter (arcade)
Mexico 86 (arcade)
Castlevania - all the nes ones