Interesting concept, But I couldn't finish it. I gathered 2 black things but didn't get any clue ^^' ? I don't get it.
The idea was really clever, but I would have prefered to be able to shoot when I want, instead of a auto-fire.
The graphics were simple but clear and efficient. The audio was nice, even though sometimes, there were too many sounds everywhere (because of the auto-fire, I guess ^^).
Overall, that's a good idea that just needs a bit of tweaking and refinement , but still an enjoyable experience =) ! Good job !