Action Replay

Action Replay is a cheating device that you hook up to your selected game console to make in-game events easier, harder, or wierd. The gadget will do multple things for your game, such as giving you ultimate life, ammo, and so on. It can also give you characters that you couldn't before, such as in Super Smash Bros Melee where you could unlock 4 characters that you wern't able to unlock any other way.