Storynexus was the only way to easily make games exactly like FL, and as you say it is no longer supported. So unless you want to begin from scratch yourself, which would require a decent programming skillset, that isn't very realistic.
I think your best bet would be Twine (https://twinery.org/) which is a flexible choose-your-own-adventure software that can simulate all of the things possible in the Fallen London model if you work with figuring it out. Inkle Writer (https://www.inklewriter.com/) is an easier but more straightforward choose-your-own-adventure model, but can also simulate "areas + stories with required qualities".
> And Arcane Assension by Andrew Rowe. You get attunements: summoner, enchanted, diviner, elementalist, guardian, etc etc.
u/Amazinguy_11 put together a rad attunement quiz exactly for this sort of thing.
> planning to have them design an interactive fiction game this year. We probably won't be able to use the actual software, but we could do it in something like Google Sites or Slides.
Have you looked at Inklewriter? https://www.inklewriter.com/
You can use it completely in-browser, and it's purpose built for this sort of thing.
Title: Rebellion
Genre: Fantasy/Interactive
Word count: 500
Type of feedback: any kind, I just want to know if I'm loosing my time.
Inkle's games are made in Unity using Ink as the story engine.
Inklewriter is a different technology that Inkle isn't involved with developing anymore.