GuildWars

From Blizzard's New MMO Wiki

Guild Wars is an episodic series of multiplayer online role-playing games developed by ArenaNet and published by NCsoft. Although often defined as an MMORPG, the developers define it as a CORPG due to notable differences from the MMORPG genre.It provides two main modes of gameplay—a cooperative role-playing component and a competitive player vs. player component—both of which are hosted on ArenaNet's servers. Three stand-alone episodes and one expansion pack were released in the series from April 2005 to August 2007.