Hi, Uhanimar, I know of three cheats for the PC, but none of them are invincibility cheats.
There's the level select cheat, in the menu you press the arrow keys in this order while holding shift: down right left right left right left up. Then there's the movie select cheat, it's the same thing except in this order: up left right left right left right down. Finally, there's the level
skip cheat, which works ingame, it basically takes you to the next path.
It's the same thing again, just in this order: left right up down left right.
P.S. I hope these were the right cheats, as I can really only remember them well when I want to use them.
