NES: Mario 3
SNES: Super Metroid
N64: Hard to pick...Super Mario 64 or...
Gameboy Color: MGS
Gameboy Advance: Mario Kart (I totally forgot the games I used to play on this system)
PS1: Final Fantasy VIII
Xbox: Ninja Gaiden Black
Gamecube: Metroid Prime
PS2: Hard to pic...MGS3/2 or FFX...
No new-gen games because it hasn't ended yet.