Nice work, I like the minimalist graphics and the pace of play. The gameplay in the second level is much harder in the first because the viewport doesn't move until the player get to the very edge of the window, so you can't see the eight balls until they're about to hit you, so you can increase the horizontal edge of the viewport to fix that. I would also add in a reset for when the player falls below a certain y value so you can reset play and don't have to reload the game. It could be interesting to vary the speed and direction of the eight balls so there's a little variety to the challenges.