After the "rust disease" broke out in 2045, the global industrial chain collapsed, electronic equipment instantly rusted when exposed to the air, and metal became a non-renewable resource. Humanity has retreated to underground shelters, but key materials are hidden in the remains of the old era on the surface. The logic of survival has shifted from "technology driven" to "resource plundering". Violent groups, scavengers, and underground businessmen have formed a deformed ecosystem. The monetary system has collapsed, and "equivalent exchange" in barter has become the only law.
