Origin of the disaster: In 2073, an unknown "eclipse light" suddenly appeared around the world (lavender light visible to the naked eye, penetrating clouds without hindrance). It did not come from the sun, and its source remains a mystery.
- Biological level: Humans exposed to corroded light will develop "photocorrosion syndrome" within 12 hours. The skin will ulcerate in the early stage, and the body will be alienated in the later stage (such as limb distortion, loss of mind), and finally become an "altered body" that attacks indiscriminately; most animals will be directly alienated, and plants will mutate crazily (some are poisonous, and some can provide special resources).
- Material level: Metals will corrode quickly in light corrosion (steel will turn into brittle slag within a day), plastics, glass and other materials will slowly melt. Only "old wood" (trees that have grown for more than 50 years before the disaster) and "rock steel" (black rocks in specific mountainous areas) can insulate against light corrosion.
- Survival rules: During the day (6:00-18:00), the eclipse is strongest, and humans must hide in "shadow shelters" (houses built with old wood, rock and steel caves, underground spaces); at night, the eclipse weakens (only a faint residue remains under the moonlight), becoming the only window period for humans to go out to collect supplies.
