A manhwa that takes place in our modern world but dungeons tombs with monsters suddenly popped up?
Woah.
EDIT: Unoriginality aside, this is actually one of the best manhwa belonging to this very specific 'genre' that I've read.
Good pacing with art that is consistently solid without lazy and rushed scenes (like many of these korean/chinese web manga).
MC is the archetypal 'rogue' and they've managed to make him quite likeable whilst staying true to the theme of his character.
I often see these more 'ruthless' MC's either become boring one-note characters with no redeeming features or flip flop around behaving inconsistently just to fit the authors narrative.