World-Ending Spirit Skeleton

Thirty-five thousand years from now, humanity will be struggling on the brink of extinction, yet people will still fight among themselves. Just as the last spark of humanity is about to go out, one lucky man accidentally becomes immortal. He decides to use what little strength he has to restore Planet Earth. He trains desperately, builds up his own forces, conquers humanity, subdues demonic beasts, and repels alien invaders. How far will he go in the end? No one knows. The door to his destiny has only opened a crack...