8. Infinite Oxygen
The Grand Theft Auto series has come a long way since those days in Vice City where you'd be "wasted" having spent more than a couple of seconds in a body of water. Ever since San Andreas back in 2004, the player has been able to swim and even dive underwater in some cases, which heralded the "infinite oxygen" cheat code. This works in the same way as a health code might, or even an invincibility cheat, in that you can stay underwater for as long as you like or need to without drowning. And this code might come in particularly good use given that Rockstar are giving us an underwater world to see and explore in GTA V.