Hi.
(I'm posting this here because to me it seems game-programming related, but if you think it should be elsewhere, you can move it)
I saw this on Wikipedia:
http://en.wikipedia.org/wiki/Noclip_mode
No-clipping can conflict with other elements of the game. For instance, in Duke Nukem 3D, and the Commander Keen series, having no-clip and walking outside the level area causes death, and if the player has god mode activated the game will be left in an infinite loop or crash due to the way god mode was implemented. In most source ports for Duke Nukem 3D, this problem is corrected and it instead behaves more like Doom.
I'm curious about this. Now, Duke Nukem 3D's source code has apparently been released under free license (GPL), so I suppose one could dig through it and/or run experiments, though I don't feel like doing it right now. What would cause this phenomenon (namely that going out of the level in "noclip" mode kills you), from a programming point of view? As it doesn't seem at first obvious that this kind of thing would occur.