Cheat Explanations

[jmv3597]

Could someone please explain what all the cheats do?

[Alphaunit]

Knockback - each time you fire a portal you get force back (can allow for moonjumping)
bullettime - slows down time (Matrix)
huge mario - turns mario into a giant which can destroy everything (NSMB mega mushroom)
Goomba attack - causes a ton of goombas to spawn
sonic rainboom - basicly, if you exit a portal loop at terminal velocity you shoot out with a sonic boom (My little pony)
playercollision - haven't tried yet but i assume it means in multiplayer, you can stand on other players

[renhoek]

have you even unlocked them? just beat the original levels
clearly stated on the menu.
also if you do have them then why are you asking?

[trosh]

sonic rainboom is when you leave a portal not towards ground at terminal velocity