Setting: The mystery of "Akenia Adventure!" (The Other World)

Outer World scholars know frustratingly little about the Otherworld. While they often eagerly interview Dimensional Strays about the subject, two primary difficulties arise: 

1) There is only so much any given individual can know about their own world (indeed, some strays know remarkably little about their home) 

and 

2) There is certainly more than one "Other World"

As result, much of the information collected amounts to little more than scattered trivia and is very difficult to bring together into a cohesive study without a vast network of information that few academics have access to. Even then, their remains little way for them to verify any of the facts they've received. It is a grueling effort made all the more frustrating by a single, alarming discovery.

The Otherworld (one of them) seems to know a great deal about Outer World.

Well, at least a great deal about one Aeon and one place from Outer World. This has been learned through Otherworld portable devices (that have been loaned, recovered, donated, confiscated, etc) and a particular interactive function they all seem to share called Akenia Adventure!

While at first blush Akenia Adventure! seems to be mostly for entertainment purposes, experts on the 3rd Aeon agree that it is a remarkably accurate simulation of numerous places and events from the period. There are some artistic embellishments, but none greater than one might see in say, the differences between the various regional productions of the play The lover of the Shadow Queen. On top of this, there are multiple iterations of Akenia Adventure! including ones that seem to focus on wider strategy and tactics as opposed to events viewed through the lens of a particular individual. Sixteen editions have been documented, and it seems like there are potentially more.

All fascinating facts, but it begs the question, how? It seems unlikely that the Otherworld would manage to recreate (admittedly, dramatized) versions of Outer World events by coincidence alone. There are many theories, but the most widely accepted one is that some Akenian Mage-Knight escaped into the Otherworld during the 3rd Cataclysm and somehow levied their lived experience and personal knowledge to gain footing and fortune in their new home. After all, sorcerers in the 3rd Aeon were said to be able to draw Dimensional Strays into their world via ritual, so why shouldn't the reverse be possible? And, given the caliber of the dimensional strays interviewed thus far, it's believed that even the most banal re-telling of Outer World events would seem colorful and fantastic to them.

Others have put forth the suggestion that maybe a clever Otherworlder might have managed to find some way to go back and forth between dimensions, but that theory is generally considered to be very unlikely.