Half a century ago, a rogue star passed through the solar system, depriving the earth of most of its heat and leaving behind alien radiation that could cause biological crystallization and mutation. The earth has entered an ice age of "absolute zero". Human survivors have built huge dome cities called "heat source barriers" around geothermal vents deep underground. The technology inside the barrier is so advanced that it even retains some of the pre-catastrophic cyberpunk technology, which is monopolized and controlled by major "heat source chaebols" (such as Aurora Heavy Industries, Blackwater Defense, and Spark Gene). Ordinary people without barrier identities are lingering in the ruins of the ice field at minus 50 degrees Celsius, relying on steam exoskeletons, geothermal moss and excavation of pre-catastrophic ruins to survive.
Frost-dyed (mutated variant): Creatures contaminated by ice and snow radiation will grow blue ice crystal cores in their bodies, possessing extremely strong cold resistance and supernatural powers.
