Summoning completeled.
I fear interactive cinematic will be too difficult for participants to make, because it means multiple scenarios and multiple amount of work. Even though it is a really unique idea.
I would suggest something similar to Cinematic Contest #6, where any theme is possible, basically no theme at all. This would surely provide more freedom and may be more attractive for the participants, meaning any idea may be possible without enforcing theme and slicing off a portion of potential participants. Less limits, more freedom, more participation. Because right now there is a big problem, very few end up finishing their work.