Enter one of the following codes at the Enter Cheat screen. Then, start a game and pause. Now enter the cheat menu and set each enabled code as desired. All cheats entered can be saved after reaching a save point.

Function - Code

Big Cheat - BEWAREOBLIVIONISATHAND 
Tiny Enemies! - PIPSQUEAK 
Baby's face on gold tokens! - AAHGOO 
Jaun (Winner of Iguana Contest) to be on the Health Icons! - HEEERESJAUN 
Invincibility - GAMEGOD 
Infinite Lives - ICANTDIE 
All Weapons - GOODIES 
Unlimited Ammo - DONTSTOCKUP 
Big head mode - UBERNOODLE 
Stick man mode - HOLASTICKBOY 
Big hands and feet - STOMPEM 
Small enemy heads - PIPSQUEAK 
Pen and ink mode - IGOTABFA 
Gouraud shading - WHATSATEXTUREMAP 
Blackout mode - LIGHTSOUT 
View Credits - OLNYTHEBEST