Activision Blizzard and social-gaming company Zynga are being sued for alleged patent infringement.

Walker Digital, an "invention" company started by Jay Walker, the founder of Priceline.com, filed the suit in U.S. District Court in Delaware earlier this week, alleging that the companies are violating its "Database driven online distributed tournament system" patent.

The patent was awarded to the company in 2002 and includes a "product and method of distributed electronic tournaments for a plurality of players that exchanges information with a central controller to influence game play while a player plays in the tournament and stores player information to influence game play in a subsequent tournament."

Walker Digital alleges in its lawsuit that the tournament-style gameplay it patented has been used by Activision Blizzard through online gaming services and by Zynga on the Web in several games. The lawsuit specifically targets Call of Duty: Black Ops, DJ Hero 2, and World of Warcraft (along with its expansions), among others in Activision Blizzard's library. Mafia Wars and Vampire Wars were among the Zynga titles cited in the lawsuit.

Walker Digital is seeking damages, which the company says have yet to be determined.

Neither Activision Blizzard nor Zynga immediately responded to request for comment.

(Via TechCrunch)