Chaos 0 is the final, ultimate form of Chaos, and while you fight against him in the game, he is not a playable character.
However, you can play as:
* Chaos: You can play as Chaos in his earlier forms, such as Chaos 1, Chaos 2, and Chaos 4, by collecting the seven Chaos Emeralds during the story mode. These forms can be accessed in the "Adventure" mode after beating the game.
* Shadow: Shadow the Hedgehog is a playable character in the game and shares similar abilities to Chaos, especially in his Super Shadow form.
While playing as Chaos 0 is not an option, you can still experience his power and destruction through the story mode and enjoy playing as other characters with similar abilities.