Aion - also known as Aion: The Tower of Eternity - is a pay-to-play massively multiplayer online role-playing game, developed and published by NCSoft. It was released in November 2008 in South Korea, July 2009 in Japan, and September 2009 in North America, Europe, and Australia.
Aion features eight classes and two racial factions, and both player versus environment (PvE) and player versus player (PvP) content. It also features a three-faction PvP system in which the third faction is AI-controlled, making it a "PvPvE" system. The game also features a robust crafting system, a flight system that begins at an early level, and companion pets.
Aion's first expansion, Assault for Balaurea, was released for free in September 2010.