It turns out the new Batman: Arkham City game recently announced by Rocksteady in Game Informer has been in the planning stages for a while -- there are hints in Batman: Arkham Asylum that the cape and cowl adventure would expand its borders. A secret room hidden in the back of Warden Quincy Sharp's office has actually held concept art and a map of the upcoming sequel this whole time.

Players who finished the Spirit of Arkham quest to 100 percent the game will also know that Sharp has some extra agendas goin -- and don't forget that one of the domains registered by Warner Bros. for the sequel is "StopMayorSharp.com." So it appears that Rocksteady has already built story ties between the two titles.

Lead narrative designer Paul Crocker also tells GI that the second game will "shed new light on the events you saw in Arkham Asylum," too. Hopefully that means we'll (spoiler!) finally find out what's up with that little surprise scene after the credits.

This article was originally published on Joystiq.