Nice and refreshing idea. The up/down movement are very punishing. I didn't understand it was a snake like at first because I was dying to much on top/down limit. Like the möbius ribbon effect. Great job.
Thanks for the feedback! I think I suffered a bit from the "I played this game so much during development that I underestimated its difficulty for a new player"-syndrome. I've gotten the suggestion to add some "grace frames" before crashing into something as a way to be more forgiving, which I quite like.