ACHIEVEMENT - HOW TO UNLOCK Against The Odds - Completed the Single Player game on Elite difficulty. Aint Got Time To Bleed - Finished "Interface" single player level without using any health packs. Born to Kill - Killed a total of 25 aliens in single player. Break Out The Arsenal - Used all weapons and items in the game. Campaign Veteran - Single player completed. Elite Force - Killed 50 aliens in a row without taking any damage. Fighting Light - Finished a single player level without using any items. Hard To Kill - Finished Co-op Assault level 1, 2 or 3 with no player losing a life. Killing Spree - Killed 20 aliens in 30 seconds. Knowledge Is Power - Picked up 100% of the logs. No Stone Unturned - Found all secret collectibles. Team Veteran - Complete "Hydroponics" in Co-op Assault.