The space station Aspir-Hadora, galactic junk recycling plant, is threatened by Rath-tha, a giant mothership from the planet T'ufo. The invaders want to destroy the recycling plant, so that the whole galaxy fills with space garbage. Conventional weaponry is useless against Rath-tha, only professor Locaten's experimental spaceship (built according to ancient legends he heard on the planet Freak) has a chance against the invaders.
Rath-tha is a classic top-down shoot'em up. The player must battle against hordes of enemies across 4 stages while dodging enemy fire and ships. Destroyed enemies leave behind space junk that can be collected for various effects (energy boost, extra points, keys to pass through bareers).