HS, exactly.
The staff would be basically you and me. You compose and I'll draw. The key word there is compose -- the users would somehow determine the course of the story. That influence would be the core of the contests. The winning "suggestions" would have to be screened for quality and verisimilitude. Then even after all that, you and I would retain the ability to alter the winning "story thread" as needed. Finally, I think an overall story arc would have to be in place to that end. Only you, me, and the mods would know about that.
The goal would be to try and follow that arc to resolution.
Please feel free to completely hack this apart. I just want some structure to start with. This may need to be taken to PMs to now too.