Mystara is one of the oldest D&D settings. It appeared first in the module Isle of Dread, which probably many players remember and was published in 1981. Originally Mystara was called The Known World and is probably of all the D&D settings out there that has most things in common with Middle-Earth.
Mystara, developed by Lawrence Schick and Tom Moldvay, was a diverse and interesting setting. There were three different continents, Brun, Skothar and Davania, and a large archipelago called Alphatia. You had all the standard D&D races; elves lived in Alfheim, dwarves in Rockhome and halflings in the Five Shires. TSR published much material for Mystara in the 80’s, especially setting material in many Gazetteer books, focusing on different parts of the world. Early 90’s TSR published the Hollow World, which was a campaign setting set in The Known World. The old Blackmoor setting was also retconned to have existed in Mystara’s past, though perhaps many true Mystara fans don’t see that as canon. Two moons govern Mysara’s night sky, Matera and Patera. Matera is a moon similar to Earth’s moon, where the Immortals, Mystara’s deities, lived in a city called Pandius. Patera on the other hand was invisible and it’s inhabitants had a culture similar to medieval Japan.
The standard D&D setting
When Schick and Moldvay, both game designers for TSR at the time, were told that they could not use the Greyhawk setting for their material, they appealed to TSR to use The Known World, a setting they had created for their own games. The setting was heavily inspired by the works of H.P. Lovecraft and his aspirations of creating a shared fiction universe, as Schick’s and Moldvay’s setting was meant to be expanded upon by other gamers. Thus The Known World became the standard D&D setting.
The Known World is first mentioned in the module X1, The Isle of Dread, which many older players probably remember. The Known World was expanded in many modules and source materials, especially the Gazetteer, in which the setting was referred to as The D&D Game World.
TSR got many different authors to write the Gazetteers and one could say that Schick’s and Moldvay’s ideas of the shared universe came to fruition, for all the work published in the Gazetteers was later compiled, blended and combined, creating the fantasy setting Mystara.
Many parts of the Known World became legendary, e.g. The Savage Coast, which was a long coast line west of the Known World, where swashbucklers and pirates ruled. But for most parts, the Known World was a Tolkienesque, high fantasy setting which was had much in common with our world. Many cultures and nations were influenced by Earth’s history, e.g. Thyatian Empire was based on the Byzantine Empire, Glantri resembled medieval western Europe and the Northern Kingdoms had much in common with Scandinavian kingdoms.
The Known World was therefore accessible and easy to use. You could find your campaign a place in it, whether you wanted Arthurian knights, Arabian themes or Mongols.
New edition, new boxed sets and new ways
When AD&D replaced D&D Mystara didn’t get much attention from TSR for a few years. In 1994 TSR published the boxed set Kingdom of Karameikos, which included a campaign setting book on Stefan Karameikos’ kingdom. It also included a couple of short modules, that took place in the small village Threshold, sheets with pregenereted characters and a CD.
Using a CD, containing tracks with background noises and NPCs talking, when playing modules was introduced in the First Quest boxed set. TSR published many modules for Mystara which relied on the use of CD’s, e.g. Night of the Vampire and Hail to the Heroes.
Though TSR and later Wizards gave up on publishing modules with CD’s, I can’t help but admire their willingness to experiment and for trying to expand the ways of conveying module material to players.
The Hollow World
The Hollow World was a setting within Mystara, which took place inside the Mystara planet, building on real-world legends of the Hollow Earth, and published in 1990. The setting was written by Aaron Allston and used many elements from the Known World. Still, it was unique and in Hollow World you could find many different cultures, e.g. the remnants of the ancient Nithians, which were similar to ancient Egypt, and strange elves. The people of Hollow World worshipped different Immortals and magic behaved differently than on the surface.
Though the setting didn’t seem to enjoy much fame, there were a few modules published for Hollow World, I find the most noteworthy ones to be the HWA series, Nightwail, Nightrage and Nightstorm.
The Savage Coast
The Savage Coast was originally a part of the Mystara Campaign Setting, though it was later spun off and developed as a separate campaign setting, which was published in 1994 as Red Steel.
The Savage Coast, which first appeared in the module X9, The Savage Coast, was a long coastal area, where swashbucklers, pirates and other scum and villainy ruled supreme. Still, the area was plagued by the Red Curse, which eventually killed anyone who didn’t wear the metal cinnabryl in contact with the body.
Computer games and novels
Mystara was probably most famous as a video arcade game. In 1993 Capcom created the arcade game Tower of Doom and three years later Shadows over Mystara, which both used the D&D setting Mystara. The games were side-scrolling hack ‘n slash or beat’em-ups with minor roleplaying elements. Both of these games have been republished for computers and consoles as Dungeons & Dragons: Chronicles of Mystara collection.
There were also a few novels published for Mystara in the 90’s. The Dragonlord Chronicles, written by Thorarinn Gunnarsson (an pseudonym for an American author), got mixed reviews and never saw the same fame or reception as the Forgotten Realms or Dragonlance novels.
Though Capcom’s arcade games were republished and updated for modern consoles, Mystara is probably nowhere mentioned in WotC’s publishing plans, at least to my knowledge. The setting hasn’t seen any material for 3rd, 3.5 or 4th edition and I guess that it is on the same shelf as Maztica and Al-Qadim.
Still, if you are interested in Mystara you can find some information on fan sites like Pandius.