Batman: Arkham Asylum is a 2009 action-adventure game developed by Rocksteady Studios and published by Eidos Interactive in conjunction with Warner Bros. Interactive Entertainment. Based on the DC Comics superhero Batman and written by veteran Batman writer Paul Dini, Arkham Asylum was inspired by the long-running comic book mythos. In the game's main storyline, Batman battles his archenemy, the Joker, who instigates an elaborate plot to seize control of Arkham Asylum, trap Batman inside with many of his incarcerated foes, and threaten Gotham City with hidden bombs. Most of the game's leading characters are voiced by actors who have appeared in other media based on the DC Animated Universe; Kevin Conroy, Mark Hamill, and Arleen Sorkin reprised their roles as Batman, the Joker, and his sidekick Harley Quinn respectively.
The game is presented from the third-person perspective with a primary focus on Batman's combat and stealth abilities, detective skills, and gadgets that can be used in combat and exploration. Batman can freely move around the Arkham Asylum facility, interacting with characters and undertaking missions, and unlocking new areas by progressing through the main story or obtaining new equipment. The player is able to complete side missions away from the main story to unlock additional content and collectible items. Combat focuses on chaining attacks together against numerous foes while avoiding damage, while stealth allows Batman to conceal himself around an area, using gadgets and the environment to silently eliminate enemies.
Development began at Rocksteady Studios in May 2007, with a 40-person team that expanded to 60 people by the project's conclusion after approximately 21 months. Among others, the game design was inspired by Batman-penned works of Neal Adams and Frank Miller, and Grant Morrison's Arkham Asylum: A Serious House on Serious Earth graphic novel. Built on Unreal Engine 3, Arkham Asylum's production underwent several variations, refining both gameplay such as the combat system, and the central story, resulting in the removal of plot elements and some of Batman's main enemies, who did not fit the tone of the rest of the game. Rocksteady began developing ideas for a sequel months before Arkham Asylum's completion, hiding hints to the sequel within the game.