Promising, but missing key functionality
Most importantly: there is no audio. I could live with no music, but there’s not even sound effects. Who’s ever heard of a silent rhythm game?
Beyond that, there’s no level selector that I can find. After you play a level, it’s gone forever. This is particularly odd as it grades your performance with stars (3 = no missed beats), so there’s no way to see if you haven’t beaten any levels perfectly, let alone to go back and play them again better.
Those are really my only serious complaints, I guess. It’s also pretty simple (only squares, no angles) but I’m only at level 21, so maybe that gets added later? Without a song to sync to though, that’s maybe for the best…
(Come to think of it, possibly a level selector gets added later too, but I don’t see any reason to withhold that from the user even from the beginning.)