He's A Bit Mad
What's left to spoil of Arkham City? It feels like Rocksteady have let slip, either intentionally or unintentionally, every location, villain, plot-point and even pre-order secrets with their bullish marketing campaign. It's all a little silly, really; it comes across as desperate, when in reality we're all eagerly awaiting Arkham City's release, marketing or no. We've yet another leak to report, sadly, with a popular Batman villain's inclusion outed by Sony US show, Qore.
So, who is the not-so-mysterious villain? It's the Mad Hatter, a long-time Batman foe who's often depicted as a criminal genius in control of devices that can warp a person's reality so the Hatter can control them. Rumor has it the Hatter in Arkham City will feature much in the same way as Scarecrow did in Arkham Asylum, with a series of self-contained levels and narratives away from the main game and setting.
Check out the video below, where the Mad Hatter appears for a brief second - literally - at the 3:39 minute mark. He's shown while Rocksteady's Sefton Hill is chatting about the super-villains you can track down as part of the side-missions scattered across Arkham City, suggesting the Hatter will have a mini-narrative all to himself.