I Traveled Through Prehistory and Actually Wanted to Exterminate All Civilizations

Ding dong! The civilization extinction system has been activated! This system will help the host exterminate all civilizations and reunite the universe! Ding dong! Main mission released! Exterminate all civilizations and reunite the universe! Newcomer mission released, exterminate any Graystone civilization! ... A hard-working worker accidentally traveled to a strange world, where dinosaurs and monsters were rampant, humans had not yet fully evolved, mysterious witches were performing bloody sacrifices, terrifying demons harvested faith, and aloof gods looked down on the world. And I want to destroy it all! ? This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.