my best game ever = super smash bros or Deus Ex
close runners up: portal, cs, half life (all games), fallout 3,
and one that I heartily reccomend to people who like to shit themselves over and over: condemned....
N64: Either Super Smash Bros, mario kart or mario party
PS2: Gran Turismo 5 (addiction factor)
PS3: CALL OF DUTY 4 or 5 i dont care their awsome
Game Boy: Easily pokemon or dragonball z
Legend of Zelda: Occarina of Time
Tetris
Pac-man
Super Mario 64
Splinter Cell
Bomber Man
Super Smash Bros
Street Fighter II
Age of Empires
Rainbow Six [any Tom Clancy game for that matter]
ohhhhh, Streets of Rage lol and the impossible Battle Toads