Some quick feedback for you:
Right at the beginning, where the 'SPACE TO JUMP' tutorial message appears. Jumping out of the cave where 'To JUMP' hovers can be a bit tricky. If you jump even a fraction too early, you'll hit your end on the top of the cave and miss the jump. You might take a tile off the ceiling (or maybe extend the ground 1 tile out past the opening of the cave) so it's easier to jump out of the cave without bumping your head.
Really not a huge deal, I actually made the jump perfectly on the first try the first time I was playing. It was only when I went back to play through again that I noticed it.