An oddity of a teaching tool
In Search of the Unknown presents itself up as something of a teaching tool, using a stock your own dungeon mechanic, but in this area, it really doesn't come close to Zanzer's dungeon.
In Search of the Unknown does very little to break down and slowly introduce the games mechanics, and while the choose your own adventure in basic, with which B1 was packaged, had covered some of this function, I think the black box does a much better job of teaching the game.
Background and emergent narrative detail
The background of B1 In search of the Unknown can be summed up as:
Two powerful adventurers built a fortress inside a big rock. Before it was finished,
they disappeared off to fight some barbarians.
To say this is light, is an understatement. Things arn't that much improved either by the legends, or the emergent narrative details of the dungeon. We learn the wizard is doing research, which is super unsurprising, and that Warrior had a mistress and a favored companion. The Oldenhaller Contract, it is not. If I were going to run it, this would need to change.
There are some cool maps in the early days of DnD. This is not one of them. Any running of this would require a remapping of the adventure site into something more interesting and reasonable..
So far, I have generally been pretty down on this scenario, but don't get the impression that I do not like it per say. The adventure is full of awesome material, in the form of description and set dressing. While the adventure lacks a story dig your teeth into, it has some cool room descriptions to make use of, such as the entrance way with its magic mouths and hidden sally points. On top of this, the description of the adventure site itself is super cool.
The adventures stock your own dungeon monsters and wandering monsters are entirely adequate, but nothing to write home about. However, they arn't especially well thematically linked to the site.
There are a number of pretty good traps, especially the laughing gas.
This adventure has some potential, but it needs work. two possible approaches present themselves.
The first is the easiest. salvage the best material from the adventure and get rid of the rest. I would probably steal the material from the wizards section of the adventure site and some utilitarian rooms and place them in a small fort. Then add some thematically appropriate monsters.
Alternatively, a complete overhall could be done. A new backstory and emmergent narrative, in which the owners disappeared suddenly some time ago, and the adventurers are sent out to find out what happen could work, especially if, once they arrive, the site shows signs that the wizard and the warrior had fallen out, and turned on one another, resulting in a battle within the dungeon, which killed both and the majority of their servants. It would require re-mapping the sight, generating a tighter focused set of encounters, and some alterations to room descriptions.
My over all decision? A complete overhaul into a Mega-dungeon!