Here are some cheats and tips for the game Doom.
Secret Level Passwords:
Enter these passwords to enter the hidden levels.
The Military Base: 6LC!2FYTHK
(Accessed from Level 3, Toxin Refinery)
Fortress of Mystery: VZH96K4YMP
(Accessed from Level 15, Spawning Vats)
The Marshes: NM3BJ67SZ1
(Accessed from Level 29, Twilight Descends)
The Mansion: 8R!3WDDGDB
(Accessed from Level 44, Suburbs)
Club Doom: WWYZ8SSZSQ
(Accessed from Level 58, The Mansion)