The shareware version of the game was originally released on January 29, 1996, while the full version was released on April 19, 1996 as version 1.3d. The "Plutonium PAK", an expansion pack which updated the game to version 1.4 and added a fourth eleven-level episode, was released in November 1996. The "Atomic Edition", a standalone version of the game that included the content from the "Plutonium PAK" and updated the game to version 1.5, was later released; the original version of "Duke Nukem 3D" has since been discontinued. An official fifth episode was released on October 11, 2016 with "20th Anniversary World Tour" published by Gearbox Software. After fifteen years in development hell, a direct sequel was released in 2011 called "Duke Nukem Forever".