Bullet hell is a great choice for this jam. I like how insanely fast you can get the square to go even if the speed is hard to control. The parry ability is a nice touch too, but didn't seem completely reliable and I think it needed a bit more work to fit well into the game design.
Also, glad to see another solo-dev-whose-game-is-about-a-shape-surviving-in-the-void-while-trying-not-to-be-killed-by-other-shapes-in-the-void!