This might be a late comment, but when I was playing on Thursday (on keyboard mode because I didn't realize you could switch to mouse until later), the cannon wouldn't fire unless my mouse was pointing on the screen in the active part (where the deck is).

As soon as my cursor was in that area, the space bar would fire and all of it would work.

In the very first game I played, the keyboard worked fine for me. Now I can't get either control to work for me. Sometimes it will shoot a few cannon balls but then randomly stop again. I've tried refreshing and still no luck. :/