During the game, enter one of the following codes:
Invincibility: iddqd
All weapons + keys + ammo + 200% armor: idkfa
Berserker strength: idbeholds
Invisibility: idbeholdi
Full automap: idbeholda
Anti-radiation suit: idbeholdr
Light amplification visor: idbeholdl
Walk through walls: idspispopd
Chainsaw: idchoppers
Level select: idclev[episode number][map number]