Mollakan Myeonggaui Player

Lee Yun, the youngest son of the Sermin family, a prominent house on the Dreia Continent. The once peaceful family descends into ruin after the disappearance of his father and brothers. And in the moment everything collapses, Lee Yun is captured by the Paton family and meets his end after horrific torture.
But when he opened his eyes, he found himself not in reality, but in Adeon; an endless battlefield and playground of the gods. In that place where countless players lost their lives, Lee Yun grew into the Ghost King, a master player who mastered all classes: Assassin, Necromancer, and Ghost. He challenged the gods. He met his end in defeat, but his story did not end there.
The moment he awoke again, he had returned to his childhood at age twelve, retaining the power of a player. To prevent his family's downfall and reclaim everything lost, Ri-yun now begins transforming reality into his own game board. His first target is bloody vengeance against the Paton family, another great clan that destroyed the Sermin family and killed him.

(Source: KakaoPage, translated)