This is the 1981 edition of the D&D Expert Rulebook by Dave Cook, which was sold as a counterpart to the Moldvay D&D Basic Set.
The Dungeons & Dragons Expert Rules (1981), by David "Zeb" Cook, was released simultaneously with the second edition Basic Rules (1981) in January 1981. For the first time ever, it offered the opportunity to achieve levels 4-14 in TSR's introductory game.
Beyond Basic. The story of Basic D&D begins with J. Eric Holmes simplifying the original D&D rules (1974) as the first Dungeons & Dragons Basic Set (1977). After that, TSR didn't put any more work into the Basic D&D game, instead focusing on AD&D (1977-1979).
Enter the "James Dallas Egbert III affair" (1979), where a college student disappeared and D&D somehow took the blame in the media. Ironically, this controversy caused sales of Holmes' Basic Set to soar and resulted in a new directive for the newly created Design Department at TSR: supplement Basic D&D (which only covered levels 1-3) with Expert Rules that would allow players to play "through at least 12th level of experience."
What Could Have Been. When Gary Gygax first announced the upcoming Expert Rules in The Dragon #35 (March 1980), he said they would include "new classes, spells, magic, monsters, and so on." There were indeed magic item, monsters, and spells, but sadly no new classes.
Gygax had also planned for a "D&D Companion Set," which would carry Basic D&D characters from levels 15-36, but that would not appear under the Moldvay/Zeb "B/X" edition of Basic D&D. Instead, that desire would have to await the Frank Mentzer revision of Basic D&D, which began in 1983.
About Those Level Limits. Levels limits for demihumans were a point of contention in both Basic D&D and AD&D. However, they make a lot more sense in the "B/X" presentation. Though halflings, elves, and dwarves are limited to 8, 10, and 12 levels, respectively, that's not necessarily a big deal when the game only went up to level 14.
Enter the Wilderness. The original D&D divided adventuring between "the underworld" and "the wilderness," but prior to the release of the Expert Set, almost all published D&D adventures focused on dungeons, caverns, ruins, and monstrous lairs. The only real exception was the eponymous T1: "Village of Hommlet" (1979), and that was a far cry from the wilderness hex exploration suggested in original D&D. Moldvay's Basic Set didn't just keep with that dungeon-delving trend, but offered it up as the norm, saying in its introduction, "At the start of the game, the players enter the dungeon…"
The Expert Rulebook went against all of these early expectations by saying bluntly, "Adventures will take place outside the dungeon." It goes on to provide tips for conducting a wilderness campaign and specific rules for wilderness travel of different sorts. The resulting "hex crawls" would be very different from the "dungeon crawls" that D&D was built on.
The Expert-level adventures would all be largely wilderness focused, highlighting a category of adventure that wasn't seen before or afterward - at least not at the same level.
In the mid-80s, wilderness adventures occasionally snuck into other game lines - including adventures like the Basic Set module B8: "Journey to the Rock" (1984) and AD&D's N2: "The Forest Oracle" (1984) - but those adventures tended to be constrained railroads rather than the wide-open hex crawls of some Expert modules. AD&D's biggest push into the area, the Wilderness Survival Guide (1986), was never nearly as successful as Expert D&D's wilderness exploration.
Expanding the 'Known World'. The Expert Rulebook's other historical first was its introduction of the Known World of Mystara. The rulebook contains a one-page describing the Grand Duchy of Karameikos (along with some of its inhabitants) followed by a single-page hex map. This inclusion would kick off the Cook era of the Known World (1981-1986), when it was still a pretty wild and unpopulated place, before the Gazetteers filled it in more (and dramatically increased the population). The Known World professed by Cook is largely depicted in the Expert Set adventures and in B6: "The Veiled Society" (1984).
The Known World had actually originated in a shared-world D&D campaign that Lawrence Schick and Tom Moldvay had run in Kent and Akron, Ohio. The campaign setting had included a bit of everything, drawing on ancient history, medieval history, various real-world myth cycles, Tolkien's Middle-earth, Leiber's Lankhmar, Vance's Dying Earth, and Howard's Hyborian Age.
In 1981, when TSR was looking for something other than Greyhawk to use as the setting for the new Basic D&D games, the Schick & Moldvay world seemed custom-made to purpose, as it had already been designed to be expanded upon by many GMs. Thus was the Known World born.
The Inevitable Adventure. The Expert Rulebook was packaged in a box with module X1: "The Isle of Dread" (1981), which was prepared simultaneously with the Expert Rules and also features some of the first details on the Known World as envisioned by Moldvay and Cook.
About the Creators. Though Cook had previously written A1: "Slave Pits of the Undercity" (1980) for TSR's Slave Lords tourney, the Expert Set was his biggest project to date when he took it on. Cook would work his way through a few of TSR's other lines in the next few years - including AD&D, Boot Hill, and Star Frontiers - before returning to the Known World around 1983.
About the Product Historian
The history of this product was researched and written by Shannon Appelcline, the author of Designers & Dragons - a history of the roleplaying industry told one company at a time. Please feel free to mail corrections, comments, and additions to firstname.lastname@example.org.