Lastly, you should really make it longer. It was a fun game, but I completely finished it in 30 minutes. I'm not trying to say negative things about the game, I'm just trying to give you things to make the game better. I really liked it.
I finished in 30 minutes, and it was getting kind of stale at the end. If you do it again, I think you should make more enemies, and make it more than just a rapid bullet hell. Make different kinds of bullets, like ones that explode, or smaller ones that go faster. Also, you should do something with the stars. Right now, they're just there for a completionist, but they're also really easy to get, so it doesn't give the same satisfaction when you get all of them. I think you should make another upgrading screen for the stars. For example, the abilities could be upgraded by stars, or you could buy add ons with them. And the stars are much to easy to get. Maybe if you had one or two floating around the screen, and the others are gotten by doing certain things, like completing with no damage taken, killing all creatures, getting all of the coins, things like that.