Interactive Theatre
I've been thinking a lot about the idea of balancing audience participation and storytelling. I've mostly been on the side that audiences can't get a satisfying story out of such an experience if they get too much input on the story arc.
A few years ago, I came up with the concept of a play that involves in Act I a series of characters each completing a dating profile on their computer. Then, the audience would vote on which two characters they think should go on a coffee date. During intermission, the director and writer gather and read the input, which might include notes as to why they want the two characters to meet. In Act II, the two actors of the chosen characters would then improvise the date itself.
It's not a huge amount of interactivity, but it's enough to drive the story and drastically alter the ending. Also, it's "replayable" -- the audience can go to multiple viewings and make different choices. You never know which two characters will wind up on the date, nor do you even know if they will be together. I love the idea that it's not just the audience that participates in the interactive portion, but actors as well.
When I was living in France, I spoke to a French director who was wild about the idea. I don't know if it would have the same reception here. In fact, I don't know how it would go over here at all.
Anyway, it's something I'd love to write but I don't have the time. Maybe something like this exists already?