The novel that I recommend to you is 'Underworld Emperor of Online Games'. The male protagonist fell into the Underworld due to a terminal illness and began his exciting life. In the game, he had defeated the BOSS to obtain the Divine Weapon and killed the Demon God to obtain the secret technique. His opponent, Hades, had also entered the game and overthrew the rule of the Nether Goddess. The male protagonist used the Underworld Emperor's name to kill his way overseas in order to restore the country's glory. I hope you like my recommendation. Muah ~