What Kind of Immortality Do You Want to Cultivate? the Country Took Me to Bulldoze the World of Immortality

Foundation building? I have decades of skill with this gun, but I don't know if you can withstand it. Golden elixir? Can you hold my rocket launcher? Become a god? How should you respond if I pull out a nuclear bomb? You said you are the Immortal King? If you have anything to say, tell my space-based cannon! This is a story about a protagonist who uses his hometown's technology to become domineering in the world of immortality!