Speaking during a panel at last weekend's Chicago Comics & Entertainment Expo (seen by ComicBookResources.com) Batman voice actor Kevin Conroy revealed that the upcoming Batman: Arkham Asylum sequel will be very dark, reminiscent of animated feature Batman Beyond: The Return of the Joker.
"It's really, really dark," said Conroy. "It involves a lot of the villains and it goes to that area - it's that dark."
In the same panel, Conroy was also tricked into revealing that Two Face would appear in the game, although after realising his slip he did clam up somewhat.
"There's a very complicated cast," he laughed. "A lot of villains are in it. I'll just leave it at that!"