At the Main menu press L2 + R2 and a Password prompt will come up. Enter any of the following codes to unlock the corresponding.

Disable Active Cheats:
000000

Upgrade ALL Monsters:
011235

One Hit Destroys Building:
071767

Unlock ALL Monsters and Levels:
141421

Unlock Demo Mode (2 Random Monsters):
082864

Unlock Display Game Version:
314159

Unlock View Ending Sequence:
667301

Immune to Projectiles:
986960

View Credits:
667302


Unlockable monsters

Unlock Cal the Squid:
Los Angeles - Play as Kyle

Unlock Croc the Crocodile:
Hong Kong - play as Rojo

Unlock Edwin the Invader:
London - Play as Wally

Unlock Harry the Yeti:
Chicago - Play as Marco

Unlock Icky the Echidna:
London - Play as Ralph

Unlock Jack the Jackelope:
Las Vegas - Play as Harry

Unlock Jill the Jellyfish:
Hong Kong - Play as Amanda

Unlock Joe the Wildman:
New York - Play as Natalie

Unlock Kyle the Cyclops:
London - Play as Kingston

Unlock Leon the Lion:
Las Vegas - Play as Ralph

Unlock Nick the Demon:
Chicago - Play as Harry

Unlock Rojo the Bull:
Chicago - Play as Kyle

Unlock Venus the Plant:
Hong Kong - Play as Croc

Unlock Wally the Warthog:
New York - play as Marco

Unlock Amanda the Armadillo:
Los Angeles - Play as Kyle

Unlock Bart the Bat:
Los Angeles - Play as Kingston

Unlock Rocky the Granite Man:
New York - Play as Cal

Unlock Shelby the Turtle:
San Francisco - Play as Lizzie

Unlock Natalie the Nautiless:
San Francisco - Play as Marco

Unlock Marco the Shark:
San Francisco - Play as Ralph

Unlock Kingston the King Cobra:
Las Vegas - Play as Lizzie


Unlock 'Super-Unlockables':

Unlock Bubba:
Unlock ALL the other monsters and get ALL the Stars on every level.

Unlock Eyegore:
Beat ALL the challenges on every level.

Unlock Philbert:
Get the PAR points for every level.