The player starts with an incomplete, and apparently ancient, letter in his pocket. It is open to doubt that this letter was originally addressed to the player. First, it appears to be an old document. Second, the player doesn't have all of it. And third, it appears to refer to a previous trip to the dungeon by somebody other than the player, and its contents make it contemporary with the goings-on there, which was obviously in the past. How far in the past is another question (more on that below).
The player awakens face-down in a room with no normal means of getting to the surface. The player is surrounded by loose buliding stones. This implies that the player fell through the room's ceiling. The question is whether he fell in accidentally or was pushed. If it was an accident, then the letter in his pocket implies he was deliberately looking for the place, probably inside a surface building or cave due to already having a torch lit. If he was pushed, then why would he have the letter? More on this below, too.
The dungeon must have had a fairly substantial "service entrance" at one time, big enough for wagons. Otherwise, how did all those huge logs, all the furniture and fixtures, etc., get down there. There appears to be no trace of this original entrance on the floorplans of the 1st 3 levels, not even a collapsed area where it might have been. So what happened to it? Or was all the heavy stuff magicked into the dungeon? I don't think the latter because this is supposedly low fantasy, but OTOH the dungeon seems to be a special place for at least some types of magic.
The dungeon appears to have had 2 occupation phases (as archaeologists would say). The 1st occupation apparently began in the distant past with the construction of the dungeon for whatever purpose it originally served. Given its size, construction would have been a major project impossible to keep secret, and had to have been done at the orders of a famous person or persons with lots of both money and power. Plus, there's got to be a huge spoil pile on the surface. But the original occupants "delved too deeply" and awakened some "Ancient Evil". This was probably the whole purpose of the dungeon, but the "Ancient Evil" proved more powerful than expected. Anyway, there were enough of the original occupants to construct and man an impressive amount of defenses in depth but they lost the battle and that was the end of the 1st occupation. Given that the dungeon and its occupants must have been fairly visible to those on the surface in the neighborhood, the disaster must have made at least the local news. However, it occurred so long ago that the dungeon is all but forgotten today. Corpses from this time have rotted to bare bones and everything else is in a state of decay, to the point that the player could fall through its ceiling. But given the small number of skeletons for such a big place, either most folks escaped or were captured and dragged into the depths.
The 2nd occupation was smaller, much less grand, and of shorter duration. It seems to have consisted of a small group of necromancers and their hangers-on squatting in the ruins, trying to tap into the "Ancient Evil" still lurking in the depths. This occupation seems to have started within the last year or 2 at most, and to have ended violently within just the last few weeks. While the original occupants mostly vanished, most of the 2nd population is still there in the form of zombies and a few non-walking corpses. Some of these zombies are no doubt the deliberate creations of necromantic experiments but the rest are probably the necromancers' former employees, overtaken by the "Ancient Evil". Anyway, none of these dead folks have rotted yet to any substantial degree and some of the blood on the floor still looks pretty fresh, so this 2nd disaster happened quite recently.
The player's partial letter appears to refer to this 2nd occupation. As it urges cooperation with the squatting necromancers, it either came from another necromancer on the surface or at least a patron of the art. So what is the player's connection to necromancy that led him to the dungeon with part of a necromancer's letter in his pocket and nothing else but a torch? There are several possibilities:
- He is the original addressee of the letter and a minion of the surface necromancer, on a mission to help and learn from the dungeon necromancers. In looking for the original entrance to the dungeon, he falls into the starting room by accident, or is ambushed, mugged, and tossed in by the local vigilance committee. And he finds he arrived too late. His boss is going to be unhappy and will probably turn him into a newt if he ever gets back.
- He is the last kidnapping victim of the dungeon necromancers, whose pressgang was out hunting when the 2nd disaster struck. Upon arriving above the dungeon, he manages to put up enough of a fight to grab the page of the letter and a torch, but is then either thrown down a hole or falls in while trying to run away. The pressgang is maybe still waiting above for him to resurface.
- He is a member of the local vigilance committe. He mugs the original recipient of the letter and then, while looking around for more evidence to report back to his buddies, he falls in by accident, losing the 1st page of the letter in the process.
- He went to the dungeon to excavate because he's either an antiquarian or a dealer in ancient artifacts, hence his lack of combat skills and equipment although he's good at digging. He is totally unaware that necromancers are squatting inside until he finds the partial letter at the edge of a collapsed area where the original recipient had dropped it as he fell in not too long before. While reaching for this scrap of paper, he falls in himself.