Space Bar Defender

Your homeworld is being invaded, and YOU must build up the defenses to protect it! You have one tool and one tool only to help you: the "Space Bar". Simply press down on the almighty key to place turrets, but be careful! You only have limited room, and limited space, and if misplaced, the turret's lost! If all else fails, you can activate the "Super Space Weapon" during a wave to stop all enemies and deal massive damage- at a cost. Will you defend your homeworld in time, or will the Space Bar run out?