Thousands of years before the dawn of civilization on Earth, Mysteroid was a thriving world home to an advanced civilization that was close to exploring the Solar System. However, a nuclear war broke out on the planet, eventually wiping out all but a small number of survivors. Despite the fact that their race had survived, these survivors were contaminated with Strontium-90, meaning that each new generation suffered severe genetic illnesses and mutations. Realizing they needed to colonize a world that wasn't ravaged by radioactivity, they travelled to Mars. Mars's lack of resources was soon felt by the Alien Race, and so they decided to invade Earth, travelling to the Moon to make their plans.