I was asked to support interactive stories for as long as I had storiesonline. I never took it seriously for many technical reasons.
However, after an author posted 5 'standalone' stories on the site and they were obviously different parts of one interactive story, I decided to add the support.
As of today, we have partial support for interactive stories.
So far we have one story to check out:
https://storiesonline.net/s/19418/my-wifes-first-teaching
There is another story that has chapter jumps embedded in the text itself that I created manually years ago, but for the life of me I can't remember it, so if you've seen it, let me know.
Authors can now choose 'interactive' in the submission wizard when submitting a new story. You can only upload the starting point chapter when submitting such a story and then you can add additional parts/chapters once the previous part has been processed and posted on the site. The system is not designed for small one paragraph branches, so such stories won't be accepted.
Each part can have unlimited number of branches. Each branch can have a link with a custom title and description. Authors can edit the title and the description of each part directly through the Manage Stories facilities.
Left to do: Zip archives and ebooks. Zip archives are doable (not soon though), but I'm not sure how to go about cross linking different chapters in EPUB or Kindle files to create the story flow tree. For now, in Zip archives and ebooks and text files, all chapters are listed in a linear fashion in the order they are submitted.