The mechanic was very satisfying and easy to understand. This would have also worked great for this year's GMTK Jam.
It would be great if you included DAS style movement so I don't have to tap as much. I was also wondering if a screen wrap could work, where you could teleport to the opposite side when hitting the current walls. Maybe that would make it too easy or feel awkward. The DAS is definitely a good idea though.
Could you artificially speed up the level progress (the number), even if you don't increase the difficulty. I was pretty slow and felt like I wasn't really making any progress. It's probably because I wasn't really getting a lot of points.
Overall, really good! Great Job!