Story graph is a state-control system for storytellers. It models a story as a set of storylines with states at every given moment.. Each state is modeled via a graph where the vertices and the edges are respectively the story objects and their corresponding relations. As the story goes by the state is modified via applying a delta of changes in moments called events.
Basically this is Git for storytellers.
We have a detailed contribution guideline that is worth the read before any contribution.