LEFT, CIRCLE, LEFT, RIGHT, SQUARE, RIGHT.

Your screen will say "Waiting For Other Players".

The other three players should hit the start button and join in.


Fatboy
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.

Four Players Without A MultiTap
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.

Level Advance
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.

Unlock Every Level
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.