From Alan Liu I learned about the Transverse Reading Gallery , a project mapping interactive narratives from the Demian Katz Gamebook Collection led by Jeremy Douglass. In an background paper on the project titled, Graphing Branching Narrative Douglass starts by asking,
What are the different forms of interactive stories? Which are the biggest and smallest, the simplest and most complex? What are the most typical and the most unusual? When we consider the structures of interactive narratives, are there local features or overall shapes that correspond to particular genres, authors, languages, time periods, or media forms?
The project web site is simple and informative. It includes a blog with short essays by research assistants. What you can see is the different topologies of these gamebooks from the tall ones with lots of choices but little narrative to the wide ones with lots of story, but little branching.