Biggest exploit in a game?

[SimuLord]

I think 100% Chameleon in Oblivion qualifies as an exploit. Being completely invisible all the time totally breaks the game.

 

[BrEnNo1023]

3 letters

B X R

if you play halo 2, you know what this means, and you love it

 

[DM.]

I can't believe i forgot Rainbow road for ALL the Mario kart games. Also the OH LOOK I CAN REVERSE OVER THE FINISH POINT THEN DRIVE FORWARD AND IT COUNTS AS A LAP bug.