Enter W93M 7H2O BCYO PSVB. This code will give you 100 health, 200 armour, all weapons, full ammo and a backpack. It'll also supply you with the three pentagram icons that make your laser three times stronger than the BFG and can kill bosses in four seconds flat. These useful pentagrams also let you use the three mysterious switches in the last level, closing the gates which spawn the monsters.