The story unfolds in the 21st century, a time when escalating pollution has prompted scientists to develop hydrogen fuel, known as HBT, as a clean alternative to fossil fuels. Amidst this environmental crisis, humans have already begun colonizing Mars to alleviate overpopulation on Earth. In 2050, a mysterious alien race called the Inbit invades the planet. The human forces are overwhelmed, leaving Earth largely desolate with only a few scattered pockets of survivors. Many refugees flee aboard the last remaining shuttles, seeking refuge on the Moon. The Inbit establish their primary base of operations, named Reflex Point, in the Great Lakes region of North America.