I followed your instructions in a previous comment and was able to start the game, it was fun!
I do feel like you should only have to shoot each thing once to knock it down, it would feel more satisfying. Then maybe just speed up the pace along the "track" if you feel like it needs to be harder?
The other thing I noticed is that after emptying the gun, when I was frustration clicking waiting for it to reload, it would restart the reload process every time I'd click and wouldn't ever actually reload until I stopped clicking.