This game has the best soundtrack of all the games from all the game jams I've played so far. And only a few commercial games have better music. Really, congrats on that. I can see myself listening to it when I work or want to focus on something. My favourite was the first one, it had nice mix between calm and dark.
The atmosphere is incredible as well. Movement feels fluid and the artstyle nicely fits with the music.
My only complaint is about the last level. There are no checkpoint, or at least they are really far from each other so I wan't able to reach some. It's such a shame because the rest of the game is amazing, sometimes quite hard, but saves on earlier levels saves the day.
Also jumping on that jellyfish were sometimes clunky, because colliders didn't really fit with the sprite.
But rest of the game is super cool and I had a lot of fun playing it.
Good job.