Return to Castle Wolfenstein is a 2001 first-person shooter developed by Gray Matter Interactive and published by Activision. A sequel to id Software's Wolfenstein 3D (1992), it uses the Quake III Arena engine and follows U.S. Army Ranger B.J. Blazkowicz as he investigates Nazi paranormal experiments during World War II. The single-player campaign spans multiple locations, blending run-and-gun combat with stealth sequences and scripted set-pieces. The game is noted for its detailed visuals, smooth performance, and a landmark objective-based, class-oriented multiplayer component that would later influence titles like Wolfenstein: Enemy Territory. Despite critical acclaim, reviewers noted uneven difficulty and a short campaign. Return to Castle Wolfenstein earned several awards and is considered a key entry in the franchise.