Zynga's complaint, filed in federal court in San Francisco on Friday, is centered around PyramidVille, a game title released by Kobojo on Facebook in early 2011.

"Facebook users are likely to believe, erroneously, that PYRAMIDVILLE is a member of Zynga's 'VILLE Family of Games," Zynga said in its complaint.

The lawsuit comes as Zynga's effort to secure a trademark for the word "Ville" has stalled in the U.S. Patent and Trademark Office.

Although Zynga does not hold a trademark for the word "Ville," the company said in its complaint that it has "consistently promoted the 'VILLE Family of Games together as a family, identified by the distinctive 'VILLE suffix."

The lawsuit is the latest in a string of trademark battles for the San Francisco social gaming company, which has been locked in a similar spat with Blingville, the creator of an eponymous Facebook game.

"Zynga's "Ville" family includes many well-known games, including FarmVille, CityVille and CastleVille, and the "Ville" suffix is strongly associated by gamers with Zynga," Zynga said in a statement Monday. "Given Kojobo's refusal to change their game name, legal action was necessary to defend our famous marks and prevent player confusion."

In recent years, Zynga has gained millions of users who pay to play its "'Ville" suite of resource-management games, which feature similar game mechanics but different themes. The company has continued to roll out new additions to the series to sustain interest from users on the ultra-competitive Facebook platform.

Zynga has asked for damages of three times the profit that Kobojo earns from PyramidVille.

Kobojo could not be immediately reached for comment.

Kobojo, founded in 2008, received roughly $7.5 million in funding from European venture capital firms last year. The game publisher was also part of a global startup accelerator program backed by Microsoft Corp, although Microsoft does not own a stake in the company.

(Reporting By Gerry Shih; Editing by Tim Dobbyn)

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