Is there cheats for Halo 3?
There are online cheats, but you will get banned instantly.
There really isn't Halo 3 cheats except for manually done cheats from the controller itself. This cheat is a way of holding down your gun like master chief in one of the Halo 3 posters. If talking about like " type in this cheat and you unlock all the maps cheat" well no. There are no cheats like that for Halo 3. :)