Interesting concept, average execution.
This was "fun" for the first couple of lifes, but it got tedious. The concept is original, or rather i haven't come across it before (the "your bullets are your own worse enemy" idea"). But it was executed without prowess.
My other main gripe is that you couldn't shoot for yourself, I would much prefer to be able to press space or something and shoot bullets. The concept would still work with some tweaking if this was done. Also add some sound effects for when you shoot. Maybe different "shapes" for enemys, EG green squares, yellow triangles, just for a bit of variety.
Nice one and good luck!