All Sniping, All the Time
Find a typewriter in the game and enter the code "LONGSHOT." This will start a mode called "Snipe-O-Rama," which gives you a sniper rifle-like zooming effect with all the game's guns.
Pause Screen Cheats
You can enter a handful of cheats by first pausing the game. To make Jimmy invincible, pause and enter "Square," "L1," "Circle," "R1," "Triangle," "L2," "Select" and "R2." Get a bullet shield by pausing and entering "Circle," "Select," "R2," "R2," "R1," "R1," "L1" and "R1." Earn unlimited ammunition for your arsenal of weapons by using the code "Circle," "L2," "Square," "L1," Select," "R2," Triangle" and "Select" while the game is paused. Unpause the game and any of the cheats you entered will activate.
New Levels and Miscellaneous Password Cheats
Enter some passwords at the "Passwords" screen, which is accessed from the main menu, to skip levels and gain more bonus abilities. Skip to Level 2 with "ORANGUTAN." Go to Level 3 by entering "BABOON." Use the cheat "CHIMPANZEE" to access Level 4. Unlock Level 5 with "LEMUR" and Level 6 with "GORILLA." Get kills with only one hit by using the cheat "WHATYOUGET." Enter "BULLETZAP" and bullets will not harm you. However, you can still take damage from punches and explosions.
Enigma Machine Cheats
As you advance in the game, you will unlock the Enigma Machine. Here, you can enter passwords that have the opposite effect of most game cheats, which usually make the game easier. These codes, however, increase this game's challenge. Use the cheat "GLASSJAW" and you will only be able to down foes with head shots. Make some enemies invisible by entering the code "WHERERU." Play in "Perfectionist Mode," where it only takes one shot to kill you, by using the password "URTHEMAN."