A good submission, the artwork works really well with the theme/concept, it plays out quite nicely and there's enough difficulty to keep your attention. The boss definitely looks awesome.
I feel that there could have more feedback for the boss, something to show that bullets aren't going to work until an opportunity arises, rather than them going right through. Turret sprites would also look and feel better if they were to face the player when shooting.
However it was an enjoyable game, well done.