Nice boss fight game ! But it is really hard !
Ways to improve : Make a first level easier with an quick integrated tutorial, make the controls snappier because the character feels heavy to move, you can add health and bonuses to pick up ...
Those are all great ideas. I mostly support the last one with the health and bonuses to pick up. The character is heavy to make you use the shield more often and the boss is hard so that you can play more time, but you are right about that I should add tutorial level, but due to the time limit of the jam I just replaced it with controls menu to tell you the controls and also to be able to change them! Thanks for your feedback! Did you see the die animation of the boss at the end? It's pretty cool ;)