I'll just add some suggestions if you don't mind.
Maps
To be fair, it's good, just that it could have been different.
Getting a non-repetitive feel often comes from small ideas. In your setting, something like a bed out of a cell could work, for example.
Puzzles / Story
Interaction-wise you could learn a lot from Corpse Party (RPG Maker game). Because of the 27 Endings (different game overs depending on the way you died), you have to make careful choices and interact with care : there are interactions just for context, some that give clues, some necessary for the good endings and some that lead to the bad ones.
Sounds / Events / Effects
I'll go with an example : when we unlock a door, we get a "you unlocked the door with the key" with a short sound and we can immediately go to the next room. Now imagine if we got instead a "use the key ? (Yes / No)", then a black screen, a slow unlocking sound, then we look at the result : sometimes back to normal and "door unlocked with the key", sometimes cutscenes, sometimes game overs... Wouldn't that be so tense ?
The sound for "yes" would be heavy, and the black screen could be red-ish.
Example for random sound using delay + black/
red screen : when you enter a room, black screen before seeing the room, loud sound (like a heavy object falling but we'll never know), then back to normal (in the room we entered) and the MC reacts "..." or "What was that...", "Who's there ?" etc. No consequence on the gameplay but the atmosphere gets haunting as sometimes black screen before seeing the room could just be a game over (suspense).
The opening strike and laugh could also use the black screen, btw. Also, the loud sound could be accompanied by a quick red screen, like in the video below.
Well, that all relies on the black screen and delays stimulating the imagination of the player. Going back to Corpse Party, even unrelated to OST it just sets text, scenes,
jumpscares extremely well IMO, especially in a RPG Maker game which kind of need that book-like stimulation because outside of CG they can't be visually that scary. What do you think about it ?