I really love the idea of exploring the level and then trying to find the ring combinaison for every upcoming challenge. I didnt know you could check the level at first, so maybe a slow autoscroll to check the level out could be nice.
I can already see where this could lead, many other type of ghosts and more challenges.
The baby is a fun idea. A bigger game could really encourage finding the right hero to bring players into the story.
Good job, I liked it :)