Các điều khiển game:
MoveAimShoot/AttackRunJumpReloadUse ItemSelect WeaponPause
Your base is now under attack by hostile aliens! Your mission is to destroy all their motherships and annihilate all the extraterrestrials that will come in your way. Defend your base and survive! Unlock all the achievements from easy to hard. Kill all the aliens and earn lots of bonus points. Compare your points and compete with others in the leaderboard!