There are two novels that meet the requirements: "My Life as a Castellan in another world" and "The Wasteland Magician." The former was a fantasy novel about swords and magic. It told the story of the protagonist crossing into the magical world and using technological knowledge to develop his own kingdom. The latter was a sci-fi novel about evolution and mutation. The protagonist relied on his own code of law and science and engineering knowledge to survive in the wasteland world. He gradually grasped the biggest trump card to stand here and used his own technology to change the story of the world. I hope you like this fairy's recommendation. Muah ~😗