Based on the popular fantasy Pen and Paper roleplaying game (based around the Dungeons and Dragons 3.5 Ruleset), Turbine's Dungeons and Dragons Online provides players with an MMO experience that sees their characters working together to fight iconic monsters, crawl through dangerous dungeons solve puzzles and more.
The game has recently seen a re-launch in the form of Dungeons & Dragons Online: Eberron Unlimited. The update has converted the game into a hybrid free-to-play & subscription model game, offering players the choice of how involved they'd like to get.