Duke It's Zero Hour

Duke It's Zero Hour is a total conversion for Duke Nukem 3D. The project was developed by ZeroHour Software and released on November 1, 1997. It features new levels, weapons, enemies, music, sound effects, and even an original boss. Duke It's Zero Hour is sometimes purported to have been an officially authorized expansion that was originally slated for retail sale via WizardWorks, but these claims are disputed.