Shroud

When the gray mist from the center of the earth submerges the earth, there will no longer be any living people in the world. Thick fog lingers low in the sky and will rise again and again. All the humans stranded in the fog area have been alienated and turned into berserkers who blindly follow and hunt, following the fog upwards, never ending. From then on, tall buildings became the ground, and the clouds and sky became the boundaries. The remaining humans segregated the buildings and retreated layer by layer, trying to survive by continuously migrating upward.