Twelve Sky, often referred to as 12 Sky, is a massively multiplayer online role-playing game (MMORPG). It is Korean developer Alt1's first released game set in the Oriental Fantasy universe launched in its home market in 2004. Aeria Games announced Twelve Sky Closed Beta on September 5, 2007. The Closed Beta date was set to be on September 18, 2007. Twelve Sky then went into Open Beta on October 12, 2007. AeriaGames announced the closing of the game on April 6 on their forums. The game officially closed on April 30, 2010 with their item mall closing on April 13, 2010.
Source: Wikipedia, "Twelve Sky", available under the CC-BY-SA License.