Agincourt Gaming ^[1], a Plano, Texas-based company and relative newcomer to the social gaming sector, has sued Zynga ^[2], the world’s largest social gaming company for patent infringement. Agincourt seeks compensation for damages and requests a permanent injunction against the company, which could shut down Zynga’s games on Facebook, including FarmVille, Mafia Wars, and Empires & Allies.

Other games that violate Agincourt’s patents include CityVille, FrontierVille, FishVille, PetVille, YoVille, Zynga Poker, Treasure Isle, CafeWorld, and Vampire Wars.

Little is known about Agincourt besides its Greco-Roman combat game on Facebook called Pantheon. However, the company alleges owning “foundational patents that claim priority back to 1996,” including concepts and processes like a credits and prize redemption system based on the outcome of gameplay.

“Agincourt’s patents cover the most lucrative aspects of online social gaming—including those comprising the bulk of Zynga’s revenues—as they contain the crucial ‘link’ that allows for global, interactive prize redemption over the Internet,” says Bill Carmody, a senior partner at Susman Godfrey LLP, Agincourt’s lead counsel.

This news comes shortly after last week’s peculiar exit ^[3] from Zynga general manager Jeremy Verba, who left the company before its plans to go public to take the chief executive position at eHarmony.

This is a pretty big blow to Zynga, a company well on its way to its desired $1 billion IPO ^[4], originally filed on July 1. Zynga delayed ^[5] its IPO by revising its S-1 filing last week, and in that revision, the company claims to have already dealt with several intellectual property allegations in the past.

Last month, Zynga launched ^[6] its first game on China’s social network Tencent, and the company still hopes to earn a valuation between $10 billion and $20 billion in its upcoming IPO.

Read more from Inc ^[7].