Gives me Geometry Wars vibes which is cool. Pretty good idea on the theme, on my second play it became obvious that I was using up all my life shooting. I think it has room to expand further.
For feedback, there were a couple of issues with screen sizing and UI going off the screen, and gameovers keep the play in motion where I have to refresh the page to replay. I also kept losing my mouse off the screen, I think you can lock it into the screen for better gameplay. If you take this further, I'd recommend adding several shooting sounds, picked randomly for every shot to add variance.