The Known World of Dungeons & Dragons began taking shape in the B/X edition, making D&D distinct from AD&D, which was set in the World of Greyhawk in the early 80s. My first contact with the Known World was from the map in the D&D Expert Rulebook (1981).
By 1990, Mystara (as the Known World would soon be “known” – ah, puns…) had been thoroughly mapped and populated far beyond Karameikos in the excellent Gazetteer series.
See also: Gazetteer series at my reference site The Eastern Countries Trail Map (1989): D&D Known World Setting
The Known World: It Isn’t Flat, But It Is Hollow!
TSR charted a new direction going inside the Known World. The project was helmed by the late, great Aaron Allston. One of my favorite RPG designers, Allston drew on drew on pulp fantasy Lost World literature – Think H. Rider Haggard, Edgar Rice Burroughs, et al – to populate the lands deep underneath Mystara’s crust.
“…this boxed set details not a subterranean realm filled with inhuman horrors or angst-filled dark elves but a lost world after the fashion of the pulp fantasies that inspired early D&D. This lost world is filled with anachronisms — ancient Greeks, Egyptians, Vikings, and Aztecs share the Hollow World with lizardmen, Hollywood-style pirates, high-tech elves, and Lilliputian animal-riders.”Grognardia – Retrospective: Hollow World Campaign Set
“…this wonderful setting be attached & used for other old school & OSR D&D style settings. … Different caverns & tunnels of the Hollow World have planar gateways into other D&D settings even though many of these are monitored & very dangerous. There’s also the ‘spell of preservation’ issues along lots of other weird bits & pieces. Plus one has to deal with the Council of Intrusion ( the council is a party of immortals whose job is to eject any demons, devils, aliens, or cosmic entities from Mystara) if you were going to do a large scale otherworldly invasions you might be in trouble. But smaller parties, lone travelers, adventurers, etc. are not even going to be noticed.”Swords & Stitchery – Exploiting The Hollow World Setting & OSR Games
Hollow World Campaign Set
1990 … Aaron Allston … TSR 1054 … 3 books, 4 poster maps … ISBN 0880388625
These box sets are now collector items, with collector prices. Gamers: If you just want to run a Hollow World game, DriveThruRPG is your go-to. You can buy in PDF ($10 – as of this writing) or Paperback reprint ($16).
Dungeon Master’s Sourcebook
I was alerted by “morphie” on the Piazza… Typo: TSR 1054XXX1901 is noted on the title page, but 1054XXX1401 on the back cover. The other two books have similar discrepancies.
The DM’s book is all-business, with little interior art.
Links to Amazon, DriveThru, eBay are affiliate links of course. I get a few coins and its costs you nothing. Thanks!
See also: Ready to deep dive into Hollow World? Check out the Hollow World subforum at The Piazza