Awesome feel
I think this game is really good, but has potential to be absolutely amazing. If you wouldn't mind just a few humble suggestions from a fellow game designer, I'd be glad to give the following ideas.
Perhaps a reloading animation? Even a little progress bar just to show how long it takes to reload. This would help me as a player to anticipate when reloading will end, and help me get my cursor back in line.
And then, just before it gets too long, a border. It might be annoying to reprogram all the scripting with new dimensions, so even I would be hestitant to pursue the following, but putting a hefty border on a game like this is a must if the target is going to go to the edge. Very frequently I would click outside of the play box, hiding it, and while it's more an issue with the NG setup, it's still a tad annoying.
I also had some other ideas regarding gun animations, showing it firing, giving a muzzle flash, a strong "bang" with each shot, whatever, but that's all just aesthetics. This is one solid game, one I really enjoyed.