I remember reading this novel like a year ago back, it was good read. A comment I read at the time that best describes this series was: "This is just like the SCP foundation"
How the story translates into a Manwha tho, I kinda prefer the Manwha a bit more because of the details in the text over imagery used in the Manwha. While the imagery in the Manwha is very colorful and pops out, at times I feel a bit of sensory overload looking at the several different objects on screen on top of the text explaining the rules of each nightmare.