In many Unreal Engine games there are several cheats that can be typed to enable noclip mode.

Silicon Knights has been forced to recall and destroy all unsold copies of their Unreal Engine games.

(e.g. Valve's Source games, GoldSrc games, Unreal engine games).

However, no known custom maps have been made because there is no level editor for the game and the developers made it impossible for players to use the level design computer program UnrealEd, which works for other Unreal engine games.

One of the first companies to do this with first person shooters, all Unreal games on the PC had the level editor included for free, and some third party Unreal engine games did the same with an edited and specialized version.