Castle Wolfenstein is a slow-paced stealth game set in World War II. The game's main objective is to traverse the levels of the castle to find the secret war plans and escape alive. Progressively higher military ranks are earned upon each successful escape with the war plans, and the game becomes correspondingly more difficult as each higher rank is achieved. There are 8 ranks, beginning with Private, culminating at the rank of Field Marshall.

World War II is raging across Europe, and Castle Wolfenstein has been occupied by the Nazis and converted into their HQ. You have just been captured behind enemy lines, and await interrogation and torture by the dreaded SS in the dungeons of Castle Wolfenstein. A dying cellmate bequeaths you your only hope: a gun and ten bullets. Your mission is to find the war plans for Operation Rheingold and escape from Castle Wolfenstein alive.