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!

i actually really like this one! it's like lumines meets... bejeweled twist? does anyone even remember that one?

i had briefly entertained a similar idea myself for this jam, but then dismissed it like 5 seconds later, thinking it wouldnt work as well LOL. glad to be proven wrong!