In Search of the Unknown was not the first adventure ever created, it was not even the first TSR adventure ever created. It was though one of the very first adventures I ever encountered and one of the first I ever ran.
The adventure is a great case of both teaching tool for learning DMs (we were all new to this once) and DIY Dungeon. Some areas are detailed, but many are not, leaving room for the neophyte DM to record what monsters and treasure were in each room. There are also a plethora of cliche spawning Dungeon tropes, that were just getting started here. Magic mouths, one-way secret doors, a mysterious creator of the dungeon, or in this case, two, and strange magical artifacts.
This adventure was the perfect learning tool for me at the time since my own version of D&D was a mix of Holmes Basic and the AD&D Monster Manual. This "Basic" introductory module was released before the Basic game, but it moves elegantly between Basic and Advanced that begs you to mix and match your rules systems. Author Mike Carr even gives some guidelines on how to use this adventure with AD&D.
The module is pretty typical for the time. 32 pages of b/w art and text. Detached cover with blue maps printed on the inside of the cover. The first 6 pages are dedicated to running the adventure and how to run this one in particular.
I have used this adventure to start every new campaign I have ever run in D&D, regardless of the edition. The dungeon crawl here is so primal that it calls out to you. A true In Search of the Unknown indeed. The one thing I never did, however, was to investigate more about who Rogahn and Zelligar were and why they left their lair of Castle Quasquenton.
One thing that B1 did give me, in a roundabout way, was my very first witch NPC Marissia. She is in the lower parts of Quasquenton and she is attempting to summon the spirit of her master Zelligar and her father Rogahn.
The adventure has stood the test of time and it is a great combination of flexible dungeon design. Nearly anything can be put into this adventure to raise or lower the difficulty as needed.
[5 of 5 Stars!]