Very fun game!
I think the game would benefit from adding a button that, if held down, speeds up the game to 2x, as sometimes, especially at start, the game feels a bit slow, and sometimes you are just waiting for your snake to keep moving forward and finally reach a certain circle or square on screen.
Also, I think changing the game's step-based movement to a more "continuous" movement, meaning you see the snake slowly moving from a tile to another instead of seeing it snapping onto it, would make the controls feel more responsive (sometimes I find it difficult to turn exactly where I want to).
Other than those minor fixes, the game is already pretty fun to play, adding some more powerup types and variety would make it even better :D