I won't give too much away but friends had recommended Sleep No More whilst here in New York; in fact they'd recommended I go more than once. However I only had the one opportunity to do this and at $100 a pop I didn't want to blow too much without knowing what I was letting myself into.
It's a massively interactive play that spans 6 floors of a huge building in western Manhattan and a story that repeats itself 3 times over the 4 hours that you're in there. Because scenes are acted out in different rooms it's probably impossible to see it all in a single show, and there are unique experiences that may or may not happen in the performance. In fact the 6th floor is invite only and anyone trying to get up there is turned away.
All the audience wear strange white masks, security/ushers wear black ones and the performers are the only people who show their faces. They're all really good performers with lots of choreographed performances.
It's clear there are people who go only to try to get the unique experiences. I met one person who was waiting for ages besides a locked door expecting it to open (I don't know if it ever did), and you can probably still have a good time just exploring the many rooms without doing that stuff. I did have a little encounter with one of the women, but not sure if that counted or not.
So, it is quite special and I'm glad I went. Would I go again? Yes, probably :)