Arda: Lord of the Rings

The world of Arda is the setting of J.R.R. Tolkien's series of Middle-Earth, most notably the "Hobbit" and "Lord of the Rings".

Eru Illuvater is the creator of Ea, the universe. In this universe he created the Ainur, who were is children. The most powerful 15 were known as the Valar, and all the others were known as Maiar. He bid them to sing of his glory and all was in harmony save one, Melkor bought discord. The creator fashioned a world in which eEves and Dwarves could live in. The creator sent the Ainur to Arda to shape the world. Over the course of centuries they would maintain Arda, as their brother Melkor caused everlasting strife.

Arda itself was considered to be a flat disk, with three great continents. Valinor, Hitherlands and the Dark Lands. They were surrounded by an ocean called Ekkaia. After the second age with Downfall of Numenor, the world became spherical. Aman was made hidden, and Middle-Earth came to be. Aman became the haven for the elves, and was called the Undying lands. The rest of the races lived on Middle-Earth

The mortal races are divided between the champions of the Valar and those of Melkor.
The Dwarves, Elves, hobbits, Human, Ents and Eagles would champion the Valar in the world.
While Dragons, Wargs, Werewolves, Trolls, Goblin, Orcs, and Spiders served Melkor.

Unlike most fantasy games, this world is its current age is very low magic. The elves are leaving, the Dwarves are all but forgotten, the Ents have lost themselves, and its is the age of man. Magic is a thing of the elder ages, and only a few know of its secrets. Also clerics are unheard of as only a select few know of the Valar, let alone Ere Illuvater. Man is faced with fighting against the champions of Melkor, unaided and alone with a few champions of light left.

This campaign setting has been supported by several role playing systems and an MMORPG.
Tolkein himself left so much great detail to this world! He even developed several languages and alphabets in the process. As with any campaign setting, you can use the Themes and history that Tolkein has set up, and as the MMORPG did breathe new life into it with keeping it as Tolkeinish as possible.