PC players may have had to wait a few weeks to get their version of Batman: Arkham Asylum (it's due out in stores this week) but they won't have to wait much longer to get the super hero action game's first free update. Publisher Eidos has announced plans to release the Insane Night map pack on Thursday, September 15 via the Games For Windows Live Marketplace.

The map pack contains two new maps. One is a FreeFlow Combat mode map called Totally Insane (that's not a joke, by the way) where you control Batman against enemies in Arkham's records facility. The other map is a Invisible Predator mode level called Nocturnal Hunter where you stay in the shadows while taking out The Joker's minions. With the game selling extremely well on consoles (it's reportedly sold two million copies since it's console release on August 25) we suspect this will just be the first of a series of downloadable extras for the game.