Hollow World

The flexibility of the Dungeons & Dragons (D&D) game rules means that Dungeon Masters (DM) are free to create their own fantasy campaign settings. For those who wanted a pre-packaged setting in which to play, TSR, Wizards of the Coast (WotC), and other publishers have created many settings in which D&D games can be based; of these, the Forgotten Realms, an epic fantasy world, has been one of the most successful and critically acclaimed settings. Many campaign settings include standard sword and sorcery environments, while others borrow Oriental, Central American, swashbuckling, horror and even space-travel themes.

These are official D&D campaign settings published or licensed by TSR or WotC. Some, like original settings Blackmoor and Greyhawk, are no longer published or officially licensed, though all have active fan bases.

A setting in which the players took on the powers of the divinely-empowered rulers of nations, with emphasis on tactical gameplay with a broad scope.

The original campaign setting played for D&D, created by Dave Arneson. Although created prior to Greyhawk, Blackmoor was only published later as part of the distant past of Mystara. In 2004, Blackmoor was again published by Arneson and Zeitgeist Games. It was also run as a Massively Multiplayer Role-Playing Game, or MMRPG, a type of living campaign. This campaign setting is no longer officially supported.

Council of Wyrms is a D&D boxed set, published in 1994, that includes rules for playing dragon, half dragon, and dragon servant characters. It includes three rule books: one for the base rules, one for dragon family and clan histories, and one for adventure modules. In 1999 it was slightly revised and reprinted as a hardcover book. This campaign setting is no longer officially supported.

...
Wikipedia