In 2037 AD, "black snow" appeared for the first time in the world. It's not snow, but a crystallized contaminant from an unknown layer of dust high in the sky that dissolves into water, soil and the human nervous system when it hits the ground.
The infected will not die immediately, but will gradually lose their "self-boundaries": first forgetting their loved ones, then losing their sense of pain, and finally being drawn into a group consciousness, becoming a monster that survivors call an "empty shell".
Three years after the end, the city was divided into three types of areas:
Safe Zone: Controlled by the old government, consortium, and remnants of the military, resources are strictly rationed.
Gray zone: where survivors gather, black markets, and refugee teams operate.
Snow area: Black snow and highly polluted area, densely packed with empty shells, but also hiding old civilization materials and "snow cores", new resources formed after pollution.
