Really fun, found myself playing this for hours while binge-ing a youtube series in another window, not sure if this is a bug or not, but my level bar increases when i rotate a piece counter-clockwise (I have that binded to Q if that helps) Being an amateur GMS2 game dev myself, i figured this was probably just a left-over debug function. But i still wanna point this out.
EDIT: I remapped my rotation keys to test and yeah, it's just Q that does that, still interesting. Also my highscore is 70498 so far.