Unlock all the unlockables
Complete the game on Hard Difficulty
Kill 2 aliens with one Rocket
Kill 15 enemies on the HMV turret
Complete a mission on Normal without dying, failing, restarting, or continuing campaign
Kill 20 enemies with a sniper rifle
Complete the game on Normal Difficulty
Watch an unlocked video
Call in the airstrike to defeat the Command Center
Survive the pool attack
Destroy the gas station
Complete the game on Easy Difficulty
