Warner Bros. liked Rocksteady Studios' success with Batman: Arkham Asylum so much they decided to buy into the privately-held developer, picking up a majority stake. It co-published the title alongside Eidos last year in North America. Arkham Asylum earned notable critical acclaim and several awards and nominations. Today, Warner Bros. says the game has shipped over 3 million units worldwide. "Rocksteady demonstrated its professionalism and extraordinary development abilities with Batman: Arkham Asylum," says Warner Bros. Home Entertainment Group president Kevin Tsujihara. "This arrangement is a great strategic fit and we are very pleased to solidify our relationship with this talented development team." UK-based Rocksteady was founded in 2004, and Batman: Arkham Asylum is its main yield (prior to that, it released only Urban Chaos: Riot Response). It's currently developing a sequel to Arkham Asylum, announced at the 2009 Spike Video Game Awards. "We are proud to strengthen our association with WBIE, a world class publisher that we have enjoyed working with since we began developing Batman: Arkham Asylum," says studio director Jamie Walker. Studio investments and acquisitions have been part of Warner's incremental gaming expansion strategy for some time. It acquired LEGO tie-in developer TT Games in 2007 and, more recently, defunct Midway's Mortal Kombat franchise and the two studios that develop it, for example; it also was a major investor in Eidos prior to Square Enix's acquisition of the Tomb Raider publisher. "With the successful release of Batman: Arkham Asylum, a franchise that is a key focus for Warner Bros., Rocksteady has proven that they have the expertise to create hit games with mass appeal," says president Martin Tremblay. "We are currently working with Rocksteady on the sequel to Batman: Arkham Asylum and look forward to bringing the continuation of the franchise to fans worldwide," he adds.