You guys made this art during the jam? How??? That's insane! I think the environment art is the biggest selling point here. Amazing job.
The camera also seems very polished for a jam game, I have to say.
I think the concept is interesting enough, but I think the controls could be tweaked a little bit. When I saw that the controls were "click and drag to shoot" and I even saw the "shoot arrow", in my mind that actually registered as a "charge-up meter" and that's what I thought it was initially. So for the first level I thought that shooting was done by holding down the button and releasing, which built up charge over time. Then in the second level I realized that that didn't work, and went back to dragging the mouse.
Sorry I know I'm rambling - I think what I wish to convey is: holding the button to charge up the shot felt a lot more intuitive to me, and I think that would convey more of a feeling of raw power, which could make the game more fun on a level of "juice".
Also, I totally understand the design behind having the balls fall off rather than bounce off, but again at a kinetic level, I see the game being more fun if the balls bounced off walls rather than falling down.
Other than that, I think the game is still quite fun, especially because of the art, the level designs, and the smooth difficulty progression of the game.
I would love to have your rating / comments on my game as well, so I can know what to improve too.