PASSWORDS:
B32R: Stage 1 with infinite lives
3KNT: Stage 2
MDWH: Stage 3
2S3W: Stage 4
1Z5C: Stage 5
F5F5: Stage 5 with Flamethrower, extra lives and bombs
P3LS: At the title screen, start a new game to see an Ending.
M1LZ: Allows you to play past Level 3 on Easy mode.
K4RN: Reverse the D-Pad buttons during the game.
H2F2: Stage skip
BIER: Secret stage