I think overall your game was too hard. Not being able to aim while moving around made it even harder.
Your audio is really good effects in game are cool, but being forced to stand in the same spot to be able to deal damage to each piece of boss was frustrating.
I think one way to help with difficulty could be to instead of start with 6 enemies on screen, work up to it. Like start with one, then when you kill it summon in the next 2, then when you kill those summon in 4 and then you win game.
Also I think your enemies could have really benefitted from health bars, and probably lower hp pools to add.