D!Zone 2

Doom cheats are typed straight into the running game — there is no console and no menu to open. You simply type the code on the keyboard while running through a level, and a confirmation message appears at the top of the screen after the last letter. If you are playing in the browser, click inside the game window first so the keyboard talks to the game and not to the page. The second D!Zone adds several hundred more user maps. Pick the shape of IDCLEV according to whether you are running a map on top of Doom or Doom II.

With fan-made maps, IDCLEV and IDDT are worth more than god mode: they quickly show you whether the whole collection is worth playing through or whether you should cherry-pick a few. Doom cheats are not hidden in a menu, they are simply key sequences — which is why you can trigger one by accident. They are also worth saving for a second playthrough: IDDQD turns Doom into a shooting gallery and switches off the rule the whole game is built on, namely managing ammo and health.