The Keep on the Borderlands was written by Gary Gygax as a new introductory module to go with the D&D Basic Rules. It replaced In Search of the Unknown in the original Basic Rules set and was included with the Moldvay edition of the Basic Rules throughout its publication run. The Mentzer revision of the Basic Rules did away with module B2 in favor of the castle adventure included in the Dungeon Masters Rulebook. If I had to guess, I'd bet that it was decided that a simpler adventure should be included due to the younger audience that edition was aimed at.
Being an introductory module, the first few pages consist of much the same information that was provided at the beginning of module B1; advice for the dungeon master, information on tracking time, how to divide treasure and compute experience, and so forth. Of particular note, it's stated that the module is designed for 6 to 9 players, and is intended to require multiple sessions to complete. B2 has a reputation as a challenging adventure and I'd bet that more than a few under-manned parties found themselves in way over their heads. The adventure adamantly states that smaller parties must have the services of several men-at-arms made available to them and should be advised to keep to the lower caves.
The eponymous Keep is presented as a base of operations for the players situated near the border of 'The Realm' where the forces of Chaos are forever trying to invade. Shops, temples and so on are detailed with NPCs to interact with (although not a single one is given an actual name, titles only here). The intention is clearly that the players can use the keep as a staging point to first clear out the nearby Caves of Chaos and then go further afield to whatever dungeons the DM comes up with next. In practice, I suspect a lot of parties began murdering their way through the keep for all the nifty magical loot within.
The actual adventure area is made up of nearly a dozen caves scattered in a sort of box canyon area not far from the keep. Most of the caves are populated with humanoid tribes of various types who have ongoing alliances and enmities with each other that the players can take advantage of if they're particularly clever. It's easy for the players to get in over their heads here since a lot of the tribes will call others to their aid if given a chance; in particular the goblin tribe has an agreement with a nearby ogre who is entirely capable of making some level 1 characters exceptionally dead. There's also one cave populated by an owlbear and three grey oozes.
|You'd be cranky too if you looked like that.|
We're still quite a few years away from Mystara coming into existence at this point, but it's worth noting that the Keep was given an official location in the Mystara campaign world. Like most low level adventures it's placed in the Grand Duchy of Karameikos, in this case in the mountainous region in the far north of the Duchy.
Unlike module B1, I've run Keep on the Borderlands a few times. Not many, as I tend to prefer to either use more plot-driven modules or write my own for early play, but I've definitely made use of the Caves of Chaos. Curiously enough, the parties I ran it for were actually pretty competent so I don't have any stories of utter PC failure in the face of overwhelming odds. Knowing when to retreat is, I think, the most important lesson this module teaches; there's no way an adventuring party will clear the entire cave complex in a single attempt and some encounters really require the players to be prepared ahead of time to realistically handle them.
Next week we'll continue our trek through the B-series modules with a rather infamous one. Join me for a look at Adventure Module B3 - Palace of the Silver Princess and learn why the terrifying decapus is a whole lot creepier than you might have thought.