Something I think about often is just how good the linking books from Myst are as plot devices. I own the unofficial-but-kinda-official Myst TTRPG Unwritten and I just keep thinking about how much juice this one setting element could pump into the campaign.
For those unaware, linking books are essentially a magic book that teleports you to a new location when you touch the picture on the front page. While aesthetically it's like jumping into a story book, in execution and tone it's more like a long-range teleporter in a sci-fi show; when you use one, you aren't entering a fantasy world, you're dimension-hopping*.
The specifics of how the books work, however, are where things get really interesting:
They can take you basically anywhere. There's no real limit on where the destination is, with some important caveats:
The book has to be written at its intended destination and
The destination, once set, cannot be changed. However, the area in and around the destination point can change, and the book won't really care.
You also cannot link to a place in the same Age (Myst's term for dimension/planet/plane of existence) meaning in order to use the book, you have to bring it somewhere else first.
Linking is a one-way trip. The only way to get back to where you were is to find/bring another linking book.
The book you use can't come with you.** You leave it behind when you link.
Only living things can link. Anything they're carrying goes with them, but you can't just send inanimate objects through.
Lastly, and this is key, it's a book. They're small enough to carry or conceal, but also fragile. In-canon they're more resilient to aging but are still very vulnerable to fire, water, or someone who just wants to break one with their bare hands.
This also means they can be created with relative ease; you need the right materials and technique, but once you have that all you need is the time to write.
All of this means that all sorts of story events can happen surrounding the linking book. Just finding one is a mystery in and of itself: Where does it lead? Will the destination be safe? Will I be able to get back? When an Age doesn't have a return book, anyone linking there would be properly stuck, and the society who created these books knew that and used that to create prisons. That also means that an Age could be turned into an ad-hoc prison by just taking the return book, jumping off a cliff, and letting the book fall into the ocean. People imprisoned in this way can then be freed if someone new links in with a return book, and that person might not know it was a prison in the first place!
Or how about someone getting temporary access to a location, slinking off somewhere and secretly writing a linking book to return to do some nefarious business later? Or someone taking an important book hostage? Or someone discovering a book you left behind and now they're messing with your stuff? How about tricking/forcing someone to touch a linking panel?
All of this is really rich, fun drama that would play out in all its myriad forms over the course of a TTRPG campaign, and that's before considering that the Ages the books are linking to can be practically anything. I haven't run Unwritten and I don't know how well the Fate system would work at my table, but everything I've written about here is why I so desperately want to run a campaign for my friends someday.
*Yes I know that there's debate on whether Ages are created by the writer or if they existed beforehand, this post is not talking about descriptive books (although those are also very juicy as plot devices). **Relto and any other Yeesha superpowers notwithstanding. If you don't know what either of these footnotes mean then don't worry about it.