Castle Wolfenstein is a 1981 action-adventure game developed by Silas Warner for the Apple II and published by Muse Software in 1981.

Castle Wolfenstein is a two-dimensional action-adventure game played from a top-down perspective using a keyboard, joystick, or paddles.

[5] The player takes the role of an Allied spy that has been captured by Nazis and imprisoned in a dungeon within Castle Wolfenstein for interrogation by the SS Stormtroopers.

While the spy is waiting for interrogation, a dying prisoner emerges from a hiding place and hands the player a fully loaded pistol with 10 rounds, and three grenades before passing away.

[8] Castle Wolfenstein was developed by Silas Warner at Muse Software[1] and the game's cover art was drawn by John Benson.

Within the same day, he played Berzerk, a multidirectional shooter arcade video game in which the player navigates through a maze with laser-shooting robots.

[5] Muse Software released Castle Wolfenstein in September 1981 for the Apple II and the game was made on other platforms.

[13] According to Harvey Bernstein of Antic, after its release, Castle Wolfenstein "quickly shot to the top of the charts" and became "one of the most popular games for any microcomputer".

[6] Richard Herring of Ahoy!, reviewing the game's Commodore 64 version, also complained about Castle Wolfenstein's slow gameplay, especially the long time it took to open the chests.

John Romero stated the original idea was to create a 3D Castle Wolfenstein but did not have the rights to the game during development.

[10][19] Many options for the game's title were proposed and rejected and, eventually, id Software bought the rights to use Wolfenstein from Silas Warner.

[20] The original concept of Wolfenstein 3D changed significantly because the developers decided the core of the gameplay would be fast and simple so features such as the ability to drag and loot fallen enemy soldiers were withdrawn.

[24] Multiple media outlets considered Castle Wolfenstein to be significant in the shaping of the stealth games genre.

[25] In its review of the series, Xbox Wire called Castle Wolfenstein a "proto-stealth game" that contains "innovations that would go on to become standards in the stealth genre".