Cheat List
Input these during the Credits Movie in the Main Menu section:
Invincible Mode: vision + reload + primary fire
All Upgrades: vision + acquire + secondary fire
Unlock All levels: vision + reload + acquire
These cheats have been verified to only show up and not actually carry over into the actual gameplay session. The exceptions are Unlock Levels, which unlock all stages with a score of zero and Invincibility, which applies itself quite well to the Co-Op mode.