Ultima Online (UO) is a graphical massively multiplayer online role-playing game (MMORPG), released on September 25, 1997 by Origin Systems. It was instrumental to the development of the genre, and is still running today. The game is played online, in a fantasy setting similar to that of the other Ultima games that preceded it.
Ultima Online is a persistent universe set in the mythical land of Sosaria after the time of the Avatar's defeat of Mondain. Ultima Online: Renaissance is set after Minax's defeat of Lord British. The worlds that are Sosaria have been split by the powers that are Trammel and Felucca, the moons of Sosaria. Trammel, the land of good, honor, and order, links to Felucca, the land of evil, dishonesty, and chaos via a network of moongates and moonstones. Plots evolve by design of the forces of Order and Chaos (apparently), and provide a great number of experiences for the player. Translation: think MUD with a sprite interface!