It's a fun game, great job! But I believe that with some tweaks it would be even better. :)
First there's this gigantic coin that takes up a lot of screen space. Maybe holding the mouse to shoot is better than clicking, as there are a lot of clicks. And lastly, when you die, there's this auto-restart that's so fast I couldn't even see how far I went, so a little final screen with your 'score' and a 'Reset' button would be nice.