Ether Saga Odyssey (commonly abbreviated as ESO), was a free-to-play MMORPG developed by Perfect World. The International version was released worldwide in an English-language format. Ether Saga launched its closed beta February 2, 2009. The open beta began on March 17, 2009. And was fully released on July 1, 2009. Arcgames shut down Ether Saga Odyssey on January 4, 2016. Ether Saga Online is heavily based on the Chinese novel Journey to the West.