Final Fantasy VII PS1 (Cause I just remember playing this like it was my job when it was out)
GoldenEye N64 (multiplayer mayhem)
Timesplitters PS2 (fast FPS for the console, loved this game)
Diablo II (for whatever reason this dungeon game just kept us coming back for more..)
Warcraft III and Expansion (best RTS I have played)
Counter-Strike (both CS S and regular, the classic FPS online game of all time)
Battlefield 1942 (I would say BF2 but this came first. The first FPS to make the scale larger and make you feel like you are in a war)
Wolfenstein 3d (first FPS I played...wow)
Mechwarrior ( sick game...)
and I am considering...
Forza 2 (not sure, but this driving game has got me HOOKED! more so than the GT series and its got some serious depth)
Doom (great but not the first)
Motorstorm (graphics and racing mechanics are the first of its kind, not a lot of depth)
Super Mario Bros. (cause well...its mario)
Duck Hunt (using a gun on the tv, awesome)
and im sure a ton others!