You are part of an alien race of invaders that attack planets to take over their resources to use for your own growing populace. You need to clear out all of the humans from each of the floating islands to make way for your mother ship. The longer you fight the more coins you will obtain and be able to spend inside the shop for upgrades. These upgrades range from weapons, fighter droids and enhanced thrusters that will allow you to fly around the map much faster. Keep your cross hair aimed on the humans and watch your flight path so you do not get hit by bullets. Spend your coins wisely and you will do just fine.