Kill a total of 25 aliens in single player
Complete all single player levels 1-5
Find all secret collectibles
Kill 50 aliens in a row without taking damage in single player
Complete "Hydroponics" in Co-op Assault
Complete any single player level without using any items
Complete single player levels 1-5 on Elite difficulty
Complete 'Interface' single player mission without using a health pack
Complete CO-OP Assault level 1, 2 or 3 without either player dying
Collect all the logs throughout the game
Fire every weapon and use every item in single player
Kill 20 aliens within 30 seconds in single player
