Bonus characters and level
Successfully complete the game in campaign mode under the "I Can Win" difficulty setting. A bonus level and two more characters will appear after the credits. Successfully complete the bonus level to unlock it and the new characters in multi-player mode.

Rocket jump
Pick up a Rocket Launcher and switch to it, then point your gun straight down. Jump, and when you are at your highest point, quickly fire the Rocket Launcher. If done correctly, your character will go high in the air. Note: You will most likely lose a little bit of health while doing this, so be careful.

Pause in multi-player mode
Since the game does not have a pause option in the multi-player mode, simply press Start , highlight "Quit" and press X. Your game will be paused, but it will not quit unless you select "Yes". To resume the game, select "No".

Level Skip
Hold R1 + R2 + L1 + Select, and press X, Circle, Square, Triangle, X, Circle, Square, Triangle during game play. If done correctly, you will automatically win the match.

How To Defeat The Vadrigar
On Tier 5, mission 5 on Single Player Campaign, you must face The Vadrigar 1 on 1. To Defeat Him, you must take out the shield generators protecting him. To do this, run to 1 side of the chamber you are in, press R2 to snipe and use the BFG-10K to aim at the red balls. USING ANALOG MAKES THIS EASIER. When you have destroyed the shieldgenerators, the vadrigar will go for all powerups, i would try to stop him whilst exercising caution using strafing. Try to get quad damage. If the vadrigar STOPS dead, hammer him with a rail gun 3-5 times you'll defeat him easy. Otherwise use a chaingun with quad damage and haste.