The fire of hell was extinguished and demons poured into the world. In 2901, the world was invaded by mutated rabies virus and nuclear radiation. Most of the people in the world were infected and zombies appeared. The virus is contagious to mammals. It is now agreed that it is transmitted through vaginal contact. The infected person will be transformed into a zombie within 48 hours, becoming an unconscious monster that only keeps biting. For zombies, headshots are the best way to deal with them. ABO article about doomsday zombies, finding targets while fighting monsters.