Blackmoor is a medieval fantasy roleplaying game campaign setting created by Dave Arneson. It was the first campaign setting ever created by TSR, but Greyhawk was published before Blackmoor. (The setting Empire of the Petal Throne also known as Tekumel was published prior to even that.) It was published in 09/75. Seeing as Dave Arneson is still running it, this also makes it the longest running campaign in existence.
Blackmoor and Greyhawk had frequent cross-overs, which is rather evident since there's an area of Greyhawk called Blackmoor, it also crossed over with Rob Kuntz's Kalibruhn campaign. You definitely get the feel from reading the individual books that this was a group of GMs entertaining each other, a lot of it feels like things you would only put up with in a home game. Since Blackmoor has so little material published for it, it has less of the polish that other campaigns like Forgotten Realms and Greyhawk have received.
The campaign of Mystara bears a striking resemblence to Blackmoor. Blackmoor was really the setting where most of the original D&D rules evolved. It involved not only the standard fantasy modules, but it also included steam power, gun powder, and other anachronisms, even a space ship. (If anything in a fantasy world can be called an anachronism.)
Blackmoor has the odd reputation of being imported into both Mystara otherwise known as The Known World (as a Kingdom) and Greyhawk (as a Barony). There was considerable debate as to which was the "official" location of Blackmoor, but in all honesty, it should be considered its own campaign setting. (At the time, Mystara was the default setting of Dungeons and Dragons while Greyhawk was the default setting of Advanced Dungeons and Dragons.) Arneson eventually produced additional materials for Judges Guild as First Fantasy Campaign.
Blackmoor was created as a medieval fantasy analog to a game which the early founders of roleplaying called "Brownstein." Brownstein was at its heart a wargame, but it added roles for people other than the generals who moved the troops to play (the original game was planned to accomodate 8 people, 20 showed up to play.) This worked very similar to modern How to Host a Murder Mystery party games. One player would have an agenda that they would try and convince the general, or other players, to pursue. Other players would have conflicting agendas. In Blackmoor Arenson added the concept of character advancement and it got rid of the focus on units of miniatures and replaced it with a focus on individual single characters. Arneson used Gygax's Chainmail rules for handling combat situations and spawned many modifications, which with Gygax's help, became the rules for the original Dungeons and Dragons.
The Kingdom of Blackmoor of Mystara is the pale remnant of an ancient kingdom, rich in both magic and technology, which merged the two and eventually caused a cataclysm. The only remains of that technology are the drives from a spaceship, which are now altered and the source of magic in Mystara. Despite the fact that in many ways, Mystara is based partially on Blackmoor, the division is such that it should be considered very separate. Later, several adventures were published for Mystara which featured Blackmoor campaign information. (The DA series, for Dave Arneson). These were DA1: Adventures in Blackmoor, DA2: Temple of the Frog, DA3: City of the Gods, DA4: City of Ten (which is the least canonical of the four, since Arneson wasn't actually involved). A DA5: City of Blackmoor was planned, but eventually cancelled.
The Archbarony of Blackmoor in Greyhawk was a place for where Gygax could drop in anything from Arenson's campaign that he wanted to borrow. I've heard that the City of the Gods (an unpopulated robotic city, with automated defenses) and the Temple of the Toad both appear in Greyhawk. However, otherwise it's located in northern Greyhawk and has a suggestion of powerful artifacts from another land and bears little resemblence to Arenson's campaign. In addition, the Duchy of Tenh from Greyhawk appears to have also been borrowed from Blackmoor's Duchy of Ten. They also both share a region called The Great Kingdom.
Arneson's later publication of "First Fantasy Campaign" for Judges Guild is definitely the official campaign. He also is talking about releasing a new version of it with updates for the Dungeons and Dragons Third Edition rules. As with any other published campaign, the truth is that it still is going to be a pale shadow of what you would experience if you were sitting around Arneson's kitchen table and playing the game yourself.
For more information about Blackmoor, please check the following websites:
- www.castleblackmoor.com - Dave Arenson's personal website.
- http://home.earthlink.net/~zimriel/Blackmoor/ - Home of the Ancients (very informative website)