High Quality Content by WIKIPEDIA articles! Return to Castle Wolfenstein is a first person shooter video game published by Activision and originally released on November 19, 2001 for Microsoft Windows. It was made available on Steam on August 3, 2007. The single player game was developed by Gray Matter Interactive and Nerve Software developed its multiplayer mode. id Software, the creators of Wolfenstein 3D, oversaw the development and were credited as executive producers. The multiplayer side eventually became the most popular part of the game, and was influential in the genre. Splash Damage, an independently-owned game developer in London, created some of the maps for the Game of the Year edition. A sequel, titled Wolfenstein, was released on August 18, 2009.