Woo, ancient history!
We had a couple hours to kill a couple weeks ago, and got to 13.
Today, we worked all day (except briefly while I was ordering pizza) and we made it up to 37. We figured out the answer, but didn't have time to put it in (it's the MSN level, and we figured out the trick to it).
We looked at the answer on one level, though. We were sure it was about figuring out what notes were being played, but we didn't have any means to install software that could tell us the notes. There was another one that we totally gave up on, with a picture of the creator's face. It was in the early 30s, iirc. Even after seeing the answer, I have absolutely no idea how it would be solved. But everything else we figured out!
This is a lot of fun. We have all day tomorrow and Monday to continue, I'll post how far we make it.