"Age of Mythology" shared many elements of gameplay with the main series, and was considered a part of the series, despite its different focus. The campaign in "Age of Mythology" tells the story of an Atlantean, Arkantos, and his quest to find why his people are out of favor with Poseidon. Microsoft published the game on October 30, 2002, and its expansion, "The Titans", on October 21, 2003. "The Titans" featured the Atlanteans as a new civilization. Its campaign is shorter than previous expansions, and centers on Kastor, son of Arkantos, who falls for the lies of the titans and frees them from Tartarus. "Age of Mythology" sold more than one million units in four months. It scored 89% on Game Rankings and Metacritic. "The Titans" failed to equal the sales success of "Age of Mythology", although critics rated it highly.