honestly, I think the central puzzle is way more psychological than supernatural. Sure, the island itself is shrouded in mist and whispers about cursed pirate treasure, but the real head-scratcher is why the protagonist, Captain Arlen, keeps seeing visions of his dead brother. The official logbook he finds contradicts his own memories of the mutiny.
Everyone on the crew is convinced they're hunting for gold, but the narrative subtly implies they're all trapped in some kind of collective purgatory, replaying their sins. The 'demons' might just be manifestations of guilt. The biggest clue for me was the ship's name, the Penitent, which nobody comments on. By the end, I wasn't sure if the mystery was ever meant to be 'solved' in a traditional sense, more like endured until the characters faced themselves.
It left me staring at the wall for a good ten minutes, which doesn't happen often.