I have a little idea for my game to add cheats that use keychains.
The script would make it possible to do a certain keychain and gain items/money/experience/level/hp/sp/god mode/...
So it would be like:
Up, Down, Up, Down, Attack, Defend, Up, Left, Right > God Mode
Down, Left, Up, Right, Down, Left, Up, Right, Attack > Level Up
...