cool!

Quite good!

I think that there should be a button to end the round instantly, since a lot of my time was spent waiting for the countdown to finish (even in the later rounds). Alternatively, you could make the round end automatically when you get the correct combination.

I feel like the concept could be taken further with different shapes, moving numbers, or different labels (words, equations, colours, etc.), because right now the game feels a little bit plain.

I think that the music and art fits the game, so good job!