Pitted against the Bydo Empire, the "R-Type" class ship is humanity's last hope of thwarting the impending invasion. Equipped with a sphere like object, called the "Force," this weapon contains the only form of energy strong enough to destroy the Bydo. Unfortunately, you've been chosen as the delivery system for this weapon - so it rests upon you to complete the mission.
Imagine a weaponized organic form, much like a virus, but millions of times larger and you have the Bydo. They are completely manevolent, and like a virus, seek only to infect and destroy all in their path. Mankind has fought these creatures for hundreds of years and it's come down to this moment.