To enter in the following cheats, bring up the Key Prompt during the game. Then type in:

doomsday

Then bring up the Key Prompt again and enter in one or more of the following passwords for the desired effect.

onekill off -Disable Easy Kills
invulnerable off -Disable Invincibility
hit 999 -Easy Hit Power
int 999 -Easy Intelligence
money 999 -Easy Money
str 999 -Easy Strength
dex 999 -Enable Dexterity
onekill on -Enable Easy Kills
invulnerable on -Enable Invincibility