So. Aion: The Tower of Eternity (http://www.aiononline.com/us/)

"Aion is a MMORPG with beautiful graphics, wonderful animations, and amazing gameplay,"

The World of Aion. (More info on Aion can be seen on the site)

Your adventures and travels take you to the shell-world of Atreia, once connected by Aion, The Tower of Eternity, but now shattered into two halves and a myriad of shards by an ancient cataclysm. Players will traverse these lands in their first steps on a journey to bring salvation to the world, explore floating islands, voids and other amazing vistas.

Each half of the shattered world is inhabited by one of two playable divine factions, the Elyos and the Asmodian. Isolated by the cataclysm that broke Atreia apart, each side brooded on the catastrophic events of the past and their hatred intensified for the other.

Many centuries later, fragments of the destroyed tower began to float mysteriously in the air, and soon investigations discovered unstable portals or gates that opened into an unknown place of darkness and wonder where fragments of Aion drifted. Called the Abyss, where the once-lost power of flight is now commonplace, the two races eventually discovered one another and very quickly went to war.

As the Elyos and the Asmodians uncovered new, more stable portals to the Abyss, they encountered a primeval terror that they had known only in their histories: the Balaur. Previously imprisoned within the Abyss during the cataclysm, the Balaur are the ancient enemy of all the peoples of Atreia, and it was the Balaur’s continual war that had led to the eventual shattering of Aion. Now they have returned, and the survival of both races is now more uncertain than ever.

(Information taken from http://www.aiononline.com/us/game_guide/what_is_aion/the_world_of_aion.html)