Each Generation has a game that defines that generation, and after a discussion, I decided to ask gamers what was the best game for each generation of consoles.
PS2, Gamecube, Xbox, Dreacast generation?
PS1, N64, Sega Saturn generation?
SNES, Sega Genesis generation?
PC 2000 - 2009
PC 1990 - 1999
PC 1980 - 1989
Before that (I'm not ancient)?
No PS3, 360, Wii since the generation isn't over yet, and it'll keep fanboys out of here. Otherwise have at it in the comments.