A really good concept, the art and music are top notch. The visual flairs of the boss intros are a nice touch too.
In term of gameplay, performance is a bit ropey and had a few bugs where I'd get stuck unable to move after picking up the turret.
Aiming with the turret takes bit of getting used to but the over-the-top hit flash makes it all worth while just for that.
In terms of boss design, I think you could have done without contact damage because its hard to grab your turret when its near the boss, that and the oyster spawns were too fast and didn't seem like they could be shot?
There also seems to be a lack of feedback when the player gets hit as I could barely tell when I was getting hurt.
But overall it seems like a game with potential, just a little more time in the oven to iron out the bugs and smooth that performance out. So good job on the submission