Use the following passwords at the character select screen (select 'load'):
Jungle World: TWRECKSPAD
Range Weapons: GUNSMOKE!
Desert World and Whack Angus: WHACKFAD
Pen and Ink Mode: PENCILS
Personal Weapons: UNIQUEWPNS
Hazard Weapons: HAZARDOUS
Melee Weapons: MELEEDEATH
Movement Power Ups: MOVEITNOW