I really like the artstyle and the different levels having differing themes. My bit of feedback would be three things. #1: Music. Because the game is a bit slower paced, music usually helps quite a lot in scenarios like that to make it a bit relaxing to play. #2: the doors being blacked out kinda made it difficult to figure out where the exit was at times.
And finally, progression. This is purely just my opinion, not tryna come off harsh or anything but it felt like a chore running around to find the crystals. This relates back to point 1 where there wasn't anything going on in terms of ambience either so I was just running around in silence pretty slowly. What I'd recommend in the future is to add puzzles or incorporate the crystals as some mechanic instead of it just being something you're forced to pick up and look for the exit. But then again it's just a 10 day game jam. probably can't pull all that off in this short of a timespan