This is just pure rambling off the top of my head, so bear with me here.
My idea is for a Spaceship type age. Sort of like the pod ages in design, the players are in a pod-like ship(but bigger then the pods). Different controls work the "thrusters", viewing windows, ect. It would probably require teamwork to do much useful stuff in this age, as someone would have to man the thrust controls, someone would have to see out the windows to navigate, and there probably would be some sort of power generator system connected to the pods "battery".
The pod itself charges up much like the other pods, probably off of solar energy or something. Shutting it off, like the other pod ages, also obscures the outside view as well as killing all the controls(however, the pod itself still drifts in space in it's current path due to physics). So the crew would have to work with the understanding that their pod will run low on juice, and they need to recharge it sometimes. (this is probably why you would have the "energy manager", to watch the display for juice and make sure you don't run out, or that if you are going to run out, you have already planned for it.)
The pod would also have a few "lab" like chambers on it, long abandoned of course, but there for the sake of showing that the people who used it were in fact mapping out the solar system the pod is in. They might also have a room or display near navigation controls that lock onto the nearest other body, and display info about it(mostly in D'ni text and numbers, of course).
Now...I don't know how the linking itself works, but given that we are already linking to planets, that presumably orbit suns, I gather that if the linking book described the pod instead of the space location, the book would maintain it's "lock" on that 3d point in space.
From a technical standpoint, this age would probably require a lot of coding. I guess the way it technically would work is that everything outside the pod is "simulated" to move around the supposedly "moving" pod.
We could easily limit the age to just one small star and a few planet like bodies orbiting it. There would be no way to get out of the pod, and it could even have a "safety feature" to keep it from sailing too close to any bodies in the star system(thus removing the technical limitation that these bodies are probably not going to work like real planets you can land on at all from a coding perspective). This same saftey feature could also keep the players from sailing the pod into never-never land, restricting them to the one solar system designed for the age, while giving them the freedom to navigate anywhere they please in that "playground".
I guess the storyline for the age would be that it was designed by a small group of D'ni engineers and a writer who built it and wrote it, probably as a hobby or a test of their engineering/writing. They had a grand plan to create a way to visit and explore all the universes in the sky above all the ages. Most civilizations have some people who study the stars and wished for a way to get closer, why should the D'ni be any different? Of course, reality set in, and the group had to face the fact that when the D'ni could just write a new universe to get what they needed, there was no practical need for exploring any of them. So the age would have a sort of sad history, where the group of D'ni were mostly put off as crazy by the public, and then despite their best efforts, couldn't get anyone else interested or as passionate at studying the stars as they were.
The history actually could (but wouldn't say outright, for Cyan story purposes) be what eventually inspired the "spacestation" in Myst 5. Given that Myst 5 had that spaceship, I'd venture to guess that at some point in time, the D'ni as a whole or at least enough of them were interested in the stars to develop such technology, even if they could "cheat" by simply writing more ages.
There wouldn't be any real puzzle to the age, aside from piecing together the storyline from documents and analyzing the planetary bodies in the age. But figuring out how to work the ship as a group and then being able to navigate everywhere would be a reward and puzzle in itself, I believe. The age, gameplay wise, would be a great group activity to do.
It might even be able to have an asteroid belt somewhere, just to show off some physics with the windows and be mildly exciting to sail the ship through. (the asteroids could be generic enough so that the fact they are not the same and probably randomly made on the fly is never noticed.)
Well, that's it basically all I got on this so far. It's an idea that has been tumbling in my head since seeing the pod ages in the new Uru Live. Thoughts, comments, constructive ideas, all welcome.