Beautiful graphics. I especially love the tileset, which fades away into the darkness in a very evocative way. Nice music, too.
Given how often the player will die, the spinning animation that plays after each death is too long. 1 second would have been enough.
Overall, I think the game feels too hard for a jam game. Of course many players relish a tough challenge, but in a game jam, it is best to err on the side of making the game a bit too easy rather than too difficult. (This is advice that I find difficult to implement myself, but I agree with it nonetheless. :) )