Instead, it would be other publishers who would revisit both scenarios in the twenty-first century. So Kenzer & Company first published B1 Quest for the Unknown, a version of B1 In Search of the Unknown for use with HackMaster, Fourth Edition, and would follow it up with not one, but two versions of B2 Keep on the Borderlands. First with B2 Little Keep on the Borderlands: An Introductory Module for Characters Level 1–4 in 2002, and then again in 2009 with Frandor’s Keep: An immersive setting for adventure. Another publisher to revisit B2 Keep on the Borderlands was Chris Gonnerman, with JN1 The Chaotic Caves, a scenario written for the Basic Fantasy Role-Playing Game. In addition, Faster Monkey Games published its own homage to B1 In Search for the Unknown with The Hidden Serpent, whilst Pacesetter Games & Simulations has published a number of extra encounters and sequels for both scenarios, most notably B1 Legacy of the Unknown and B2.5 Blizzard on the Borderland.
Yet Wizards of the Coast did not ignore its extensive back catalogue. It would release numerous titles in PDF, and even allow Print on Demand reprints, including both B1 In Search of the Unknown and ;B2 Keep on the Borderlands. Further, in 2017, it published Tales from the Yawning Portal, a collection of scenarios that had originally been published for previous editions of Dungeons & Dragons, including Advanced Dungeons & Dragons, First Edition, Dungeons & Dragons, Third Edition, and even D&D Next. These scenarios though, did not include either B1 In Search of the Unknown or B2 Keep on the Borderlands. Which upon first glance seemed a strange omission, but then came the announcement from Goodman Games about Original Adventures Reincarnated #1: Into the Borderlands.
The Cave of the Unknown is much like the other Caves of Chaos home to the various Humanoid tribes. Although a natural cave system with no worked areas, there are guard posts, caves and chambers for the chief of the Troglodytes, his queen, his elite warriors, both teenage males and females, and so on. A supply cavern contains boxes and crates of items gained through and trade which are perfect for adding objects and items that could be stolen or missing and perhaps serve as a possible hook to explore the caverns. Some of the cave descriptions are far from interesting, but there are exceptions. The queen’s chamber is connected to a bubbling mud pool which is difficult to traverse and fight in and she also has a pack of Cave-Dogs, specially bred by the queen so that they have immunity to the infamous stench that Troglodytes excrete. However, this does mean that these Cave-Dogs lack the sense of smell they are typically known for.
Overall, locations and encounters such as with the queen are far and few between and in this, the description of the Caves of the Unknown feels very much in keeping with the Caves of Chaos of B2 Keep on the Borderlands. They are static, all but waiting for an incursion by the Player Characters. There are potential roleplaying hooks present, although they are not explicitly stated. The Player Characters could ally with Gothmog, the Troglodyte chief, in taking his revenge on the clergy in the Shrine of Evil Chaos and their allies and the queen could be turned against Gothmog. There is also the fact that the Troglodytes are trading with someone deeper into the earth. It is not stated who, but that could easily be linked to another scenario—perhaps in the mode of G1 Steading of the Hill Giant Chief and its sequels. In any of these cases, the Player Characters will need to be more circumspect in their approach to investigating the Cave of the Unknown rather than simply slaughtering everything before them. If they do take that approach, they do face some tough opponents and a good number of them, but if they are successful, then there is plenty of treasure to be found.
BEX-1 Descent Into The Caves of the Unknown feels as if it could be something more and as if it could be more interesting. The Dungeon Master will need to work hard to bring the back story to the Troglodyte presence in the Caves of the Unknown into play and involve the Player Characters, thus turning the adventure into more of a sidequest than the side note it reads as written.