Rura Penthe

Setting
Originally known as the "Mirage Arena", this artifical world was created to train keybladers, by utilizing holographic simulations. Programs were run allowing keybladers to fight digital enemies, or tackle challenges like simulated obstacle courses and timed tests. Most often, keybladers use their own memories to feed the artifically intelligent computer matrix, which then recreated past batttles or created enemies they've encountered or witnessed. Many keybladers also fought themselves and created holographic battlefields at which to fight on.

After the great Keyblade War, the Arena fell into ruin until found by Terra, Aqua, and Ventus. They each utilized its unique capabilites to train themselves. But after each of their fateful incidents, all knowledge of the Mirage Arena was lost, and the satellite was lost, laying dormant in space.

That is until Xehanort returned at the end of KHII. under orders from his master Praetor, he began to raise an army of villains and Heartless, from across the universe. He succeeded and soon began to devour worlds in darkness over the course of the year between II and III. Xehanort's latent memories of the Arena surfaced and he rediscovered it. It became a makeshift base of operations, until work was completed on Praetor's Citadel in the ruins of what was once "Atlantica". He trained himself, and allowed the Heartless and various villains to master their skills with the holograms.

One such villain, Doctor Octopus, began to experiment with the holographic capabilites, and the AI Matrix of the Arena computer. Through this, he and Xehanort came up with a gruesome idea, transform the Arena into a gladiator-like death match. They began to kidnap the strongest fighters from numerous worlds, before eventually destroying those worlds, and pitted them against each other.