I threw together some rough story ideas whilst on the server, and eventually translated them into something to post here. Thoughts?
The player begins in a fairly normal setting, and is a treasure hunter / archaeologist of some sort looking for a set of ancient ruins based on a clue in an ancient myth speaking of something known as 'The Triumvirate'. After some searching, he comes upon what appears to be an ancient shrine: across the wall are murals and text, some of which has survived the passage of time. It speaks of three 'immortal cities', whose provisional names shall be Fallorna, Drash and Thain. It also includes a map, or directions of some kind, to the first city, Fallorna. The rest has been worn away.
The first city is found in a state of ruin, and at the center of it lies a temple. The murals in the inner sanctum of Fallorna's temple tell the player that once, the three cities were preserved, potentially for eternity, by three artifacts — one of which was stored in each city, and gives directions to the next, Drash. There should be some sort of complication regarding entering Drash and/or its temple, but once inside it is clear it has suffered a similar fate. This time the player is told how, after millennia of peace and prosperity, the ruler of Thain grew jealous of the others and stole the three artifacts for himself, dooming them all to decay. The player's next destination is an underground shrine, at the center of which, unexpectedly, is a Nether Portal, which leads to the mirror-world and the city of Thain, which may or may not be fully intact, if deserted. Eventually the tomb of the Fallen King is found, and within lies a large chest (his sarcophagus) containing bones, a golden suit of armour and the three artifacts. Whatever they end up being.
The final task is to journey through the nether to the final temple, wherin lie the three intended resting places of the artifacts (If it's starting to drag then it's as well that it be a short journey with all three positions right next to each-other, unless we're feeling really adventurous). The Player then returns to the surface via another portal, emerging in a re-built city of Fallorna. And maybe give him some diamonds. Diamonds are pretty. Or declare him king? Any sort of cool incentive.