Duke Nukem's Penthouse Paradise is an official add-on level for Duke Nukem 3D, jointly published by Penthouse Magazine and GT Interactive. It is free to download and can be played with either the original version of Duke Nukem 3D or the Atomic Edition. It was conceptualized and developed by Jeffrey D. Erb and Mark Farish of Intersphere Communications. It was released on May 1, 1997 on GT Interactive's and Penthouse Magazine's respective websites. Penthouse Paradise is the only official add-on for Duke Nukem 3D that is available for free.