Wasteland Scavenger: I Find a World-Destroying Tech Tree from the Start

In the wasteland after nuclear war, humanity has returned to a primitive way of life. An obscure scavenger accidentally discovers a fully intact vault of doomsday technology. While everyone else is risking their lives for a mouthful of clean water, he has already restarted an antigravity engine. While raiders fight over territory with crude weapons, he has built the first combat mech. While every faction assumes he is just a lucky scavenger, a private army equipped with cutting-edge technology is quietly reshaping the entire wasteland.