Various Cheats
Go to the options screen and enter the player name listed below under "Player Name". Then, exit to the game select screen and quickly press Left, Right, Square, Circle, Triangle, Triangle, Down.

GO POSTAL = Fast Reload, Damage Bonus, Unlimited Weapons
GODZILLA = Target Civilians and Friends
TOURIST = Tourist Mode

For the next series of cheats, you must enter the first code first, the Additional Options code. Then go to the options screen and enter the "Player Name", go back to the main menu and press Left, Right, Square, Circle, Triangle, Triangle, Down.

Mr Happy = Additional Options (enter first)
LIVE FREE = Invincibility
FOX ROX = City Select
MR HAPPY (second time) = Plane Select
GREG FM = All Options