The earth has an element called "lumilight" since ancient times, and there are traces of this substance in the air. Appropriate amount of lumilight can help gene evolution and accelerate the viability of species. But if it is excessive, it will produce unpredictable mutant organisms, often causing huge changes in species distribution. It happened in Ponrigio, a high-tech country that was "nuclearized" by the coalition forces due to some accidents. After the land was bombed by nuclear bombs, a large number of lumilight were detected like a volcanic eruption, and the people called it "the wrath of the earth". In order to solve the increasing number of mutants and mutant creatures due to the increasing concentration of lumilight , the government launched the "Soil Rest Project": elevating the living quarters to kilometers above the sky, away from the lumilight on the surface. There is a lack of various materials in the sky, and the most serious is energy. Fortunately, scientists have discovered that lumilight can be used as a new energy source that does not lose nuclear energy. But it needs to go to the dangerous old surface to defeat the mutant creatures to obtain it. So the government began to recruit and train "light collectors", a new profession that specializes in exploring the old surface and collecting lumilight for the government to exchange for money. Players need to use three light collectors to form a team and advance to the dangerous old surface.
