Plutonium PAK/Atomic Edition: The Atomic Edition of "Duke Nukem 3D" was first sold in November 1996, and contained the original 3 episode game as well as a new eleven-level fourth episode. The Plutonium PAK was also sold as an upgrade package to convert the first available version of "Duke Nukem 3D" (v1.3d) to the new Atomic Edition (v1.4, later upgraded again to v1.5). It includes three new enemies: the Protector Drone, the Pig Cop Tank, and a new boss known as The Alien Queen. It also includes a new weapon, the Microwave Expander, with its own special ammunition. It also has several improvements to the software of the game, which allow the game's players to create new enemies and items. Also this version includes a computer controlled second player to simulate multiplayer games.