Oh oh, the geek nostalgia pandora's box has been opened!
For arcade games, Im not THAT old (yes, Im saying you guys are) so it would have to be:
Street Fighter 2 (the original version), Mortal Kombat, Virtua Fighter
Daytona USA
For home, I started playing ALOT younger....
C64:
Blue Max
Defender of the Crown
Hardball
Winter, Summer, California Games
etc...
ColecoVision:
Spy Hunter
Gateway to Apsy (sp?)
Donkey Kong
NES:
Baseball Star
Contra
Punch Out
Super Mario 3
Ice Hockey
Blade of Steel
SNES:
Mario World
Street Fighter 2
Mortal Kombat 1,2
Killer Instinct
NHL 95
Final Fantasy 2,3
Macintosh:
Dark Castle 1-2
Police Quest 1
Sim City
(not that many mac games
PC:
X-Com
Eye of the Beholder 1,2
Land Of Lore
Doom 1,2
Rise of Triad
X-Wing
Tie Fighter
...and Im forgetting a bunch, but those are all classics.
Also,
http://www.the-underdogs.org/