It's up to you to save the world from a wave of asteroids that are heading straight towards Earth! Upgrade and buy weapons platforms between levels. Every weapons platform has the capacity to hold up to two types of ammo. Use the Q, W and E keys to select secondary ammo while using the A, S and D keys to select main ammo for platforms 1, 2 and 3. Earn cash by destroying asteroids. Automated turrets can be purchased. Turrets require visibility in order to function well. You can increase visibility between levels.