Agree with the release blockers. Certainly.
Graphics Cheats could be interesting (Press 2 on your numeric keypad to make lemmings cycle through their animations in random frame orders, or whatnot)
Or Sound Cheats: Pressing 3 will result in Tandy, VGA, Genesis, Amiga, SNES, and Master System music to play all at the same time.
Those could be interesting. I'd like to see those cheats in the game just to see what it would be like.