Nice!
I love playing your games because every time it seems like you progress and the game is a little better than the last. I like the simplicity of this game; some of your more recent stuff is really difficult to pick up and I had to just stop. I had a few problems with it though.
On the platform part, when you jump, you can't see the ground, so you can't time landings. If you actually land on a platform, it's just luck. I found it to be more frustrating than challenging. Also, in platformers, a lot of tiny platforms to stumble over can get annoying. If you timed it to bigger platforms with larger leaps I think it would be more fun. Also, collectibles! Have some coins spring up on the higher notes or something! :)
The falling blocks was pretty fun. If they stuck around longer, though, it would be more interesting because you would have to climb them. As it was I was just dodging them.
The circle level was cool, except I had an insta-death on a spike, so I'm not sure if that was right. I liked the feeling of running around the circle though.
I wasn't able to get to the last one because I didn't want to play the first one again. Anyway, it was a good idea, and implemented fairly well! Can't want to see your next one!