- In 2043, dramatic global climate change triggers the “Red Tide Catastrophe”: methane permafrost erupts from the Pacific seabed, red poisonous fog engulfs the world, sunlight dwindles, temperatures soar above 50°C, and the high-temperature Red Tide covers 70% of the Earth's surface.
- The poisonous fog is highly corrosive. Prolonged exposure causes skin to ulcerate and organs to fail, and it also spawns mutated creatures such as heat-resistant “Red Fog Lizards” and “Corrosive Worms.”
- Human survivors gather in a handful of “Fortress Cities,” relying on high-tech shields to fend off the Red Tide and mutated creatures. The cities are linked by underground maglev tunnels, and resources are desperately scarce.
