The player assumes control of three separate ships operated by three separate pilots: Alpha Ship is piloted by Yugo Tyrone, Beta Ship is piloted by Belle Vogato, and Gamma Ship is piloted by Kenny Crawford (although none of the pilots' names is mentioned in the game). Each ship has a different firing pattern, and all three of them combined together when the ships are formed together as the Moon Diver; their mission is to quell an alien invasion which is spanning all of the Milky Way, and destroy the aliens' headquarters: the Danger-Seed.[citation needed]

The player starts the game with three separate fighters and has to make it through four tubes using the fighters separately; if one gets destroyed, then the next, more powerful ship makes an attempt to get through. If the player makes it to the fifth stage, the three ships combine into a singular composite ship called the "Moon Diver", which has a massive amount of firepower - and each ship has shields, but the stages must be completed with one ship