DC Comics presents Assault on Arkham, an animated feature film that serves as a two-years-prior prequel to the Arkham Asylum video game. The voice acting credits include Kevin Conroy as Batman, Troy Baker as the Joker, and Neal Mcdonough as Deadshot. The trailer, which was recently released, showcased an organic artistic style, which seems to vaguely echo the drab style of Batman: the Animated Series; this is appropriate because the game, Arkham Asylum, was essentially a spiritual successor to and continuation of Batman the Animated Series.
Check out the IGN Rewind Theater video, which sheds light on the Arkham Asylum prequel, and provides some light discussion on such Batman media.