I have a fifth model
An explorer comes upon a concealed book which he/she leaves hidden from the DRC this is an old age previously approved by D'ni maintainers (I have a considerable back story to go with this) in this age there are Journals which lead you to further concealed linking books and Journals with further embedded clues and story.
You are following another explorer who does not like the control exercised by the DRC. I don't want to go into too much detail as the back story and the investigation is the story.
OOC The story lends itself to a self forming group of age writers willing to support the on going dialogue some of the ages are repaired others are old hidden linking books ages regarded as newly written could only host a book if the story supports the linking book having been moved to the age. This method relies on new age writers being willing to host story journals and ongoing linking books.
The ongoing story has clues that lead to the location and method of retrieving the next link/journal.
Note this methodology has already run as a Beta in UU the story is undergoing a major rewrite to comply with FCAL instructions from RAWA that were not available at the original time of writing.