Enemy of the World (Main Character Hides His Strength, Book 1/2, ongoing) by Road Warrior
Sungchul is extremely powerful. When he faces his greatest enemy however, he is held back by his inability to use magic. One thing is clear: he needs to fix this if he wants to be victorious. To gain magic powers he enters a summoning circle where participants fight for abilities, but he must hide his strength lest the deities notice and take him out before he can face the Demon King.
The translation from Korean is a little bit clunky, you can sometimes tell it’s a translation just from the sentence structure and the wording isn’t always entirely natural (e.g. “This place was about to overflow with human blood soon.”) Doesn’t completely deter from the action, just throws you off sometimes.
The book is weak on character development and relationship building and therefore relies solely on action scenes (often in the way of mindless violence and torture). The main character doesn’t really go beyond “must get stronger and murder things while not caring about anyone else”, and doesn’t even really progress all that much. The world building is fun though and differs from most LitRPGs I’ve read so far.
Overall recommended if you like OP characters, lots of murder and a fairly simple storyline. For me personally it had too many downsides though.
tw: repeated sexual assault resulting in murder (off-page and denounced)