Man, I have played so many games that it's hard to remember all of them...
I usually don't mix the console with the PC, because PC games were always more intense...
The Atari era were all so great - maybe because it was "a new technology" - but Pitfall and Pac Man still are in my memories...
Super Mario or the likes - SNES - addictive, I remember my ex-wife complaining about me and the kid playing up until the dawn...
Doom - It's on every true game player minds from the pre-history of the PC. "Fear" ? I just laugh when I remember how petrified I used to be playing in the dark with that sounds from the pc speaker !!!!
Civilization - from the first up to the III (here comes the IV) - one of the few games that never were deleted from my HD. A must have for strategy fanatics.
Tomb Raider - The first. A true amazing experience in the PS one. The plot, the sexy heroin and the 3D environment, just great at that time.
Geoff's Grand Prix series - Needless to say...
Grand Prix Legends - take a look around
Some underdogs:
Outcast - Great history, nice graphics and somehow never had a sequel...
Out of this world - that was sci fic in the top level.
Most of the Enix games - true masterpieces.