Hmm, my priorities would be thus:
- Nice feeling movement. Must be joyful.
- Obstacles (something to avoid) with collision.
- Level progression/ make at least 4 levels
- The writer writing his story at the side and making it longer as you progress.
- Making multiple routes with an idea what king of story direction it would give (different colours)
- Add assets and materials to make the game prettier and the themes stronger
- Add more levels.