Oh! So that's why Infogrames mentions the ability to hook up "3 and 4 consoles". But wait, the game only allows two players using two consoles hooked up through an iLink cable, what do I do?
Never fear, IGN is here with the answer.
LEFT, CIRCLE, LEFT, RIGHT, SQUARE, RIGHT.
Pause the game and then press:
LEFT, LEFT, CIRCLE, CIRCLE, RIGHT, LEFT, CIRCLE
At the Main Menu press:
LEFT, RIGHT, LEFT, RIGHT, LEFT, RIGHT, CIRCLE, CIRCLE, CIRCLE.
Now, enter the multiplayer option. Select how man players then at the level select screen you can highlight the MUTATORS option and hit X. Highlight the big head option and press RIGHT. now press the X button and enter the game.
To unlock a new Mutator that makes you get fatter and fatter with every Frag, and skinnier and skinnier with every time you get Fragged, just perform the following code. At the Title screen enter:
O, O, O, UP, DOWN, DOWN, UP, O, O, O.
You can now go to Multiplayer Mode and there will be a new Mutator called Fatboy. Turn this Mutator on and enjoy the antics.
All you need is a "USB" keyboard and mouse. This will also allow you to play four player via two keyboards and two controllers. Just set the controller configuration so the keyboards and mouse's are in the third and fourth player positions.
During the game you can press the START button and then enter:
LEFT, RIGHT, CIRCLE, CIRCLE, CIRCLE, RIGHT, LEFT
Once you hit the last button you'll be taken back to your game with a full ammo load-out.
During the game you can press the START button and enter:
Square, Circle, Left, Right, Circle, Square.
Once you hit the last button you'll be taken back to the game, but this time you're invincible.
While you are playing a level you can hit pause and press:
UP, DOWN, LEFT, RIGHT, RIGHT, LEFT, CIRCLE.
By performing this code you will instantly complete the level and charge on to the next.
At the Main Menu press:
SQUARE, SQUARE, CIRCLE, CIRCLE, SQUARE, SQUARE, CIRCLE, CIRCLE
Now, enter the multiplayer option. Select how man players then at the level select screen you can highlight the MUTATORS option and hit X. Highlight the STEALTH option and press RIGHT. now press the X button and enter the game.
During the game press the Start button and enter:
LEFT, CIRCLE, RIGHT, SQUARE, RIGHT, LEFT.
You'll be taken back to the game with every weapon.
To enable this code you must first play the game and create a save. From the Main Menu select Resume Game. On the Next screen highlight your save and enter the following code:
UP, DOWN, DOWN, UP LEFT, UP, RIGHT, DOWN.
If you entered the code correctly the screen will automatically change to the level select screen. It'll show you that every Level on every Ladder has been opened and is now accessible.