According to new intel, Rocksteady are working on a distant prequel to Batman: Arkham Asylum... set in the Silver Age of DC comics.
Variety reports that the next Batman game from Warner Bros Interactive and Rocksteady Studios will be set in the 1950s (known as the Silver Age), around the same time that Batman teamed up with Superman, The Flash, Wonderwoman and others to form the Justice League. The new title has been described as "highly stylised," suggesting that Rocksteady will aim to emulate the art style as well as including classic characters. Key story elements will include the first appearance of the Joker, and we assume, the formation of the Justice League.
If this report is true, we won't see Rocksteady's prequel until "2014 at the earliest." We'll keep you posted: same Battime, same Batwebsite.