Nice work. The physics have a good feel. I didn't realize there was a boss fight in the middle, and I couldn't see how many stars I needed under the lock for world 2, so I'm struggling to get enough stars to open it. Finally, I get 3 stars in all 10 levels, and the lock still doesn't open. Frustrated, that's when I tried the middle rectangle, and voila! I'm not stupid; I'm just a little off.