Kill 1000 UFOs
Complete all challenges in coop mode
Complete all challenges in a single player mode
Kill 30 enemies with a single mega laser
Detonate 30 bombs with a single shot
Kill 1000 asteroids
Have 50 asteroids in the level at the same time
Reach 500 points without missing a single shot
Kill an enemy with a deflected bullet
Kill 20 enemies in rapid succession
Reach 6000 points in arcade mode
Survive for 180 seconds
Reach 4000 points in arcade mode
Resurrect an ally in coop mode
Reach 2000 points in arcade mode
Reach 1000 points without moving