More codes that can be entered on the game title screen:

Note: "_" denotes a space

Code - Effect

WEIRDED - Change title screen colours
BETONG_ASNA - Concrete Donkey on Title Screen
CHIPRAM - Display The Free Chip Ram of Your Amiga
MUSIC - No Music On Title Screen
LITTLE_FLUFFY_SHEEP - Sheep Inside Every Crate
PESTILENCE - Spontaneous Combusting Worms
RED_BULL - Ultra High jump
MAGICAL_MYSTERY_TOUR - Worm Names Are Removed