Muse Software released Castle Wolfenstein in 1981. An innovative action-adventure shooter set in World War II Germany, Castle Wolfenstein inspired a legendary series of genre-defining titles. In Castle Wolfenstein players assume the role of an allied prisoner, later named William "B.J." Blazkowicz. They are transported to a castle inhabited by Nazi guards and assigned the task of finding secret Nazi war plans and escaping the castle alive. Gameplay is stealth-based; players impersonate Nazi soldiers and avoid detection as they explore the castle. Castle Wolfenstein is considered a pioneer of stealth-based games, introducing the stealth-based style of gameplay six years before the Metal Gear series popularized it. Castle Wolfenstein also received critical acclaim for its innovative use of digitalized voices. As players explore the castle SS guards shout commands in the German language, an unprecedented feature at the time of release. The third installment of the Wolfenstein franchise, Wolfenstein 3D, popularized the first-person shooter (FPS) genre and the WWII sub-genre, laying the foundations for some of today's most popular franchises including Medal of Honor and Call of Duty. Released in 1992, Wolfenstein 3D was the archetype for the run-and-gun style of gameplay that remains popular in modern FPS titles. The game introduced a number of innovations to the shooter genre. It featured a smooth-scrolling screen and rapid-fire gameplay, complete with an on-screen hand grasping a gun. Wolfenstein 3D also introduced on-screen ammunition counts and switchable weapons, both of which remain integral features in FPS titles. The Wolfenstein franchise consists of eight installments, the latest released in 2009. Its genre-defining titles and breakthrough innovations earn the Wolfenstein franchise an important place in the history of electronic games.