I asked this question recently(
question 23110
but I didn't give away my favourites: Elite on BBC, Manic Miner on Spectrum (still haven't finished it, even on the PC emulator), Donkey Kong I, II and III on SNES (I broke 3 controllers venting my ire on that blasted game), Crash Bandicoot I, The Tomb Raider series, Abe's Odyssey and Gran Turismo 1 on PS/1, Oddworld on XBOX (Splinter Cell is too hard), Gran Turismo 3 on PS2 and finally The Half-life series on PC. The best game, however, is Kingpin on PC (I build a machine especially to play that game). It is a great shame that they never did a sequel. I think I had Sim City on SNES but I lack the patience to play those types of games.