Hi, I want to thank you for your feedback. It will help us a lot to the improvement (for us and for our games).
I even want to tell you we know there is a piece with a boss fight that is missing (I'm one of the developers). Our initial plan was to include a final boss at the end, but we didn't have time. So we have decided to publish the game without this feature anyway. I can assure you that we will continue to develop the game and the boss will be the first thing we add.
Thanks again for your feedback and have a great day.