Nice fun little game and very nice art! I'm a big fun of slingshot mechanics and this kind of delivers. I wish sometimes it was a bit more forgiving (some kind of loose auto-aim when you're generally shooting in the right direction). I noticed quite late that the spinning radius changes depending on where you "caught" the mouse, quite interesting.
One suggestion I have is that 'game over' sfx is a bit coarse to the ear, especially since players will hear it very often. I'd recommend either removing it completely or changing it to something slightly more melodic. But it's a nitpick!