Just finished playing around a bit, so what follows is my opinion:
- Sound design is excellent. You said you loved it, but I think you also excel at it. Very well done,
- The lighting also helped set the vibe very well. I'd say in the first few platforms it was annoying that it was lagging behind, but that was less of an issue on the floating platforms,
- Platforming mechanincs are a bit too floaty, if you decide to proceed with this project I'd say focus on improving them as they felt floaty. Floaty can be good, but here the acceleration was very unsatisfying,
- There are not many mechanics, so not much to judge besides what I covered,
I think that you have very great skills in setting up nice environments with both sound and visuals. This skill could translate well in other games as well, but I could see it working on this project as well. If I were you, I'd lean even more on the horror/creepy aspects. Maybe some laughs in the background, eyes glaring at you in the darkness and so on.