Ok, so i kinda enjoyed playing this game, but there are some things:
The graphichs are meh. Now, I personally aren't really a fan of this glowy style, it looks like 1992 glowstick wars. If you make something minimalistic, do it good.
Also use some more sprites, you only have purple pentagons.
For the background, make it move or something. It bores.
The gameplay: the powerups are O.K. but make them appear more frequently and make them have a despawn time, like 5 seconds.
You can also be spawnkilled, so make invincibility frames.
The shooting is also really inconsistent which is really annoying in a bullet hell-ish game.
By the way, what are those numbers in the corners of the pentagons? I didn't see anything happen with them.
Also use some more music. Loops are better, by the way.
Ok that was it.