[Update: Playdom says it will defend itself "vigorously against this distraction”]

Social game developer Zynga has filed a lawsuit against rival online game maker Playdom and four of its employees for misappropriation of trade secrets, among other serious allegations.

In the suit, Playdom is accused of wrongfully acquiring Zynga’s playbook, which is essentially a document containing the company’s “secret sauce.” The playbook is supposedly full of non-public commercially valuable concepts, techniques and best practices for developing successful and distinctive social games, reports TechCrunch.

Playdom is alleged to have hired a number of Zynga staffers and during the process convinced them to steal and hand over sensitive information from their former employee.

According to Zynga, “The Playbook is the result of years of testing, development, trial and error, analysing customer behaviour, game behaviour, optimising past successful techniques, and collective know-how that Zynga has spent millions of dollars and more than tens of thousands of man hours developing and devising...

“In the hands of a competitor like Playdom, this document alone creates huge exposure to Zynga as it breaks down in detail and memorialises the company’s key and collective efforts to develop and fit games to the social networking platform in the most successful manner. It is a ‘how-to’ manual that belongs to Zynga.”

Zynga’s lawsuit also accuses Playdom of breach of contract, breach of the duty of loyalty, tortious interference with contracts, tortious interference with existing and prospective economic advantage and unfair competition.

The judge in the case has granted the request for a temporary restraining order against Playdom and the other defendants.

In a statement regarding the case, Playdom has said that it will “vigorously” defend itself.

“This lawsuit comes as no surprise given Zynga’s penchant for litigation,” said Playdom. “We do not believe in using unnecessary litigation as a business strategy, and we are troubled to see an industry as bright and promising as ours weighed down by such tactics. We have no interest in Zynga’s “Playbook” or “secret sauce." Our strength comes from our 111 talented people, and we will defend ourselves vigorously against this distraction.”