The Miracle Doctor's Wife is Not a Weak Lady! - Chapter 17

As a promise, he went out into the world as an assassin. 3 years later, after becoming the Supreme Assassin, he gave up on everything he had and returned to the ranks of ordinary people. But one day, Kismet, a mystical game created by the National Research and Development had appeared.

Enigmatic hands, spectral frame, and one cunning strike just like the swing of the Grim Reaper. The Supreme Assassin takes on the mystical world, and how his legendary tales sets off, progressively ascending the altar to becoming the best.

- Description from Novelupdates

His friend and his wife betrayed him. The only thing left to him was his massive debt and his precious daughter. He was without hope as he lived at the bottom. However, a last chance had come to Sungyoon. He was a ‘man without a heartbeat’, and he will explore the Moon’s Labyrinth. He’ll explore the parts of the dungeon yet to be seen!

Once, because of a pair of purple eyes he was scorned. He is a wangye known across the land, cold and bloodthirsty, looking disdainfully upon the world.