Doom Cheats

Press the start button during gameplay and then press B, Y, X, L, R, C, X, Z.

Press Start, Right, Left, Z, R, Z, L, Z, and then C to get to a special Level Warp.

Start a game and hit pause.

Press Down, Y, X, Right shift, Right, Left shift, Left, B to turn on God Mode

First, pause the game and then press Up, Down, Left, Right, X, Z, Y, A, C, B.