This is the most simple and common shooter. At the fixed outer background constantly moving forward flying ships evil aliens. This race invaders who are trying to take over Earth. You need to protect our planet from the invaders, and you can use the heavy artillery. In terms of weapons you're lucky, using orbital cannon, it can be moved in a horizontal plane and shoot without worrying about the amount of ammunition. The game has two counters, they show the amount of destruction of the enemy, the other shows the number of missing ships.