This is not a simple zombie apocalypse, but an "ecological cleansing" originating from extraterrestrial spores. A mysterious group of microorganisms called "scarlet spores" has swept the world. They not only alienate most humans into terrifying "symbionts", but what is even more terrifying is that they can drastically accelerate the mutation and evolution of the earth's animals and plants, returning the entire planet to the savage jungle law. The order and technology of the old world are vulnerable to the madness of nature.
