The Furnace Song

A modern engineer and history enthusiast accidentally traveled back in time to a down-and-out little man in the second year of Emperor Huizong of the Song Dynasty (1120). He originally wanted to be a wealthy idler, but he was involved in major events time and time again - from being an amateur on the streets to wandering the world, from becoming an official in the court to quelling chaos at the border, trying to reverse the shame of Jingkang, and finally "retired to the country and operate in secret", lighting up the technology tree with modern knowledge, and pushing the Song Dynasty to enter the industrial age ahead of schedule and move towards prosperity.