Leading social game developer Playdom and Acclaim Games, a developer of social networking and downloadable casual games, announced today that Playdom has acquired Acclaim. Acclaim was privately held and is based in Los Angeles, California. The terms of the transaction were not disclosed.

Since its establishment in 2006 under one of the gaming industry’s most recognizable brands, Acclaim has built a name for itself in the casual and MMORPG gaming space by developing and publishing free-to-play titles available on the Acclaim website. With more than 15 million registered online users already playing Acclaim’s games, the company launched RockFree, a Facebook guitar game, in March 2010, which now has tens of thousands of daily active users. Acclaim is currently hard at work on its latest Facebook game due to launch this summer.

“Joining forces with Playdom is a natural fit,” said Howard Marks, CEO of Acclaim. “Both companies share the vision of connecting people globally through quality social games. Our deep expertise in building multi player online games and Playdom’s vast player community will help us bring out the next generation of social games.”

Acclaim will become the newest team to join Playdom’s growing cadre of studios. Marks, a former Activision 2.0 co-founder and Chairman of the Activision Studios, will run the Acclaim studio for Playdom and serve in a senior strategic role for the parent company focused on Playdom’s business development activities. Acclaim’s Chief Technology Officer, Neil Malhotra, a longtime Marks colleague, will now act as the studio’s senior technical officer.