I pointed out to @der that most of us aren't as into mainstream cinema for the fantasy box office thing to work, but this idea could be a lot more fun, I think. It's mostly just an imaginative narrative being loosely constructed by user input, and as he said, requires minimal effort on the players' part. That said, I think it would be easy for anyone to throw out an occasional reply to churn out a good yarn, so I'm up for trying this out. We'll only need a few more.

Does the host participate in this, too? Or would the host just be the DM?