The original game was released as Duke Nukem during 1991 as a two-dimensional platform game, which was IBM PC compatible and featured 320×200, 16-color EGA graphics with vertical and horizontal scrolling. The original game had three episodes, the first distributed as shareware. The first Duke Nukem game was titled Duke Nukem, but Apogee learned that this name might have already been trademarked for the Duke Nukem character of the television series Captain Planet and the Planeteers, so they changed it to Duke Nukum for the 2. 0 revision. The name was later determined not to be trademarked, so the spelling Duke Nukem was restored for Duke Nukem II and all successive Duke games.