A very well made game all around, everything in it is solid and functional, only small problems to be addressed really. First being that my screen couldn't fit the entire game, I can't think of a reason why you would need a large game screen instead of small characters and enemies but ah well, its done right?
Wonderful visuals. Only things I will say are that there is very little visual difference between a regular shot and a charged shot and that all shot sprites appear to be the same sprite just with a different size or behaviour.
As I couldn't see the whole game screen I can't be sure if there was a meter or some sot of indication to let you know when a powerup was coming, if there wasn't, there needed to be. Would also give the player a reason to move aside from dodging enemy shots.
Also: I am playing on a laptop, so controlling the ship with a touchpad mouse was awkward. Try having a second control setup or laptop users. All it really means is having some keys to fire and angle your gun really.
But dont take too much of this criticism to heart, you have a brilliant game and one I have definitely enjoyed playing. 7/10