In the original Kingdom Hearts, the Olyumpus Coliseum was only used for competitions where Sora and the gang could grow stronger. This time around in Kingdom Hearts 2, the Olympus Coliseum will be something greater. You will be able to meet up with Auron and travel throughout the Underworld.

When you first arrive at the world, you will be greeted by Hercules who will take you to the Underworld with Meg, his wife. You will learn that Hades is up to his normal tactics again, trying to get rid of Hercules. This is when Hades summons none other than Auron, who is supposed to help aide Hades defeat Hercules. Auron, who knows better, decides that he will not battle Hercules. Hades, who becomes upset, tries to kill Auron himself.

After realizing that Sora and company do not have a chance against Hades since they are in the Underworld, they begin to run away. Hades is able to catch up to the group and begins to throw fireballs and summon dozens of heartless. This is where a little battle game develops. Sora and the gang along with Auron must defeat all these of heartless, but there's a catch. You must do it before a barrier breaks down, and after you finish one area, you must move onto another. And if you think that's it, there's more. Hades then summons Cerebus. Donald and Goofy who are tired flee to safety at a nearby keyhole, while you must duke it out against Cerebus alongside Auron. This is where things get fun as you get to use co-op moves with Auron and the *reaction* command.

We also learn that Hercules is unable to defeat a Hydra, which leads to Hercules breaking down. You must also help re-establish the Coliseum as it somehow become destroyed. Can Pete and Hades behind it? Other 'sidemissions' include protecting Meg from Pete, as well as facing Demyx, a member of The Order.