A really nice concept ! The last level is pretty challenging, took me a while to beat. Overall all the levels are well thought. However, I could really use a "skip tutorial" button as I'm tryharding to unlock the secret ending. (also, I don't know if it's on purpose, but a clear way to see how many times you've died and the limit you have to respect to unlock the secret level would be useful)
EDIT : I did unlocked the bonus level on my second full run, and after a lot of tryharding beated in in an unorthodox way :
The game was challenging, fun and the sounddesign and graphisms were good and created a good melancholic/desert atmosphere. I just found a "bug" : after a while, the music ends and don't loop.