Eidos Interactive and Warner Bros. Interactive, today announced that Batman: Arkham Asylum, firmly established as the ‘must-have’ game of Summer 2009, has shipped in excess of 2.5 million units to retail since launch.

In Batman: Arkham Asylum, developed by London-based Rocksteady Studios, Batman finds himself trapped inside the confines of Gotham’s psychiatric hospital for the criminally insane, Arkham Asylum.  The Joker has set a trap for the Dark Knight and has conspired with the deranged inmates to eliminate Batman once and for all.  Adding to the authenticity of the game are veteran animated Batman voice talents Mark Hamill and Kevin Conroy, who reprise their roles as The Joker and Batman respectively.

The Windows version was released just last week.