Enter NRYRDDS as a password this disables rest of the long passwords the following can now be enter:
God mode:ALL
Infinte health:HEALTH
Infinte ammo:AMMO
All weapons:WEAPONS
All keys:KEYS
All maps:MAPS
Level skip:SKIP
Sound effect test:SFX TEST
To disable cheat mode enter:PWORD
God mode
Enter S_X_N as a password. Note "_" indicates a space. This code activates unlimited health, all weapons, all keys, unlimited ammunition, all maps, and the level skip features.
Level skip
Enter NFTRWLLH as a password. Go to the map screen, and press Select to advance to the next level.
Sound effects test
Enter CRSDR as a password. Enter the game options menu, then set "Sound FX" to "Off", then back "On" to hear a random sound.
All keys...