The art style and music were very charming (could have used some more variation in the wall tileset), and the overall game was solid.
The spikes on the ground could probably be a bit more visible, maybe add some color so they can pop out a bit more (specially in the dark area sometimes they were tricky to see, being black), and not sure if it was a bug, but checkpoints only worked one time? (as in you couldn't reactivate a checkpoint to spawn there)