Warner Bros' Batman: Arkham City, released last week, has shipped more than 4.6 million units worldwide in its opening week. The Rocksteady Studios-developed title, currently available for Xbox 360 and PlayStation 3 and coming soon to Windows PC, sold through to customers a total of 2 million units during the same period, according to the L.A. Times. The original 2009 release Batman: Arkham Asylum saw total sales of 4.3 million units. Arkham City was released last week worldwide, and quickly gathered critical praise from the press and gamers alike. Thanks to significant sales in the UK during its opening weekend, the game is now the fourth biggest video game launch in the UK this year.