Final Echo: the Last Refuge

In 2035, the "grey fog" suddenly dropped, and an unknown nano-dust covered the world, which can corrode metals, decompose organic matter and induce biological mutations. Human civilization collapsed within 72 hours, and the survivors huddled in underground bunkers or fortified "arks." Lin Mo, a former special engineer, became a maintenance technician in the 7th District after retiring due to injury. Calm and pragmatic, with strong mechanical intuition and survival instinct. He controls a military-grade exoskeleton "Iron Spine" that has not been corroded by gray fog.