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