In the second year of the extreme cold apocalypse in 2124, the earth entered the eternal winter mode, and the daylight hours were shortened to 3 hours a day. A sudden change in the global climate caused an extreme cold disaster, killing 99% of the population. Existing humans have built a survival network underground in abandoned cities. In the blizzard, a nocturnal creature "Snow Charm" with thermal vision mutated, specializing in hunting humans whose body temperature is higher than the environment.
Concept: The ruins of a coastal city covered by snow, the surface temperature is always -40°C, and the survivors build shelters in the underground pipe system