Guardian is an arcade action game for one or two players. In an intergalactic war, an enemy ship called Dromeda is attacking your home planets and you need to defend them! The planets are located at either the top or the bottom of the screen, and are defended by a shield. Dromeda is in the middle of the screen, and will be launching explosive devices at the planets. You control a spaceship which is the last hope to save the planets. Unfortunately, your ships lasers are unable to reach Dromeda, so you you must shoot the explosives as they come in. If you miss any explosives, they will destroy part of the shield. If a large enough hole forms, an explosive could get through and destroy an entire planet. The game ends when all of your planets have been destroyed.