Hey thanks for the suggestions and thanks again for checking the game out and making your video. I'll respond to your suggestions below:
1. This is something we are planning on doing.
2. We have been exploring the idea of making each play-through a different / random map of stages and a boss to complete. I don't know that we will do that specifically but we are definitely planning on expanding the # of stages / making them random.
3. Yes, you are correct there needs to be a way to get back to the main menu. We will either add a button on the pause menu or on the star map.