Batman: Arkham Asylum’s demo will be available worldwide for the PlayStation 3, Xbox 360 and PC on Friday (August 7th). The demo opens as the Dark Knight and Commissioner Gordon return The Joker back into confinement at Arkham Asylum. But things soon fall apart as The Joker gains the upper hand and springs a trap, setting Arkham Asylum’s occupants upon Batman. Offering a taste of game’s fierce FreeFlow combat system and the cunning stealth of the Invisible Predator mechanic, players can …