Kill 1000 centipedes
Reach 20000 points in arcade mode
Kill 10 enemies with a single shot from a railgun
Resurrect an ally in coop mode
Reach 40000 points in arcade mode
Kill 400 scorpions
Kill 15 enemies in rapid succession
Kill 800 spiders
Detonate 50 bombs with a single shot
Kill the enemy without doing damage to it
Complete all challenges in coop mode
Complete all challenges in a single player mode
Reach 2000 points without missing a single shot
Survive for 180 seconds
Reach 30000 points in arcade mode
Kill 600 fleas