Very cute little game. I like the idea of it and how it turned out. I am not sure if it was a problem just on my side (most likely my browser being the issue), but I had some really bad FPS drops every now and then. I also managed to get stuck with the pick-ups - I was holding them and could no longer load anything anymore, nor pick up any new ones, although the cannons were empty.
Nevertheless, nice idea, and I could definitely see myself spending quite some time with it ^^