UPDATE 1-Activision wants to add Electronic Arts to lawsuit

* Asks for $400 million in damages

* Ex-employees formed studio and inked deal with EA (Adds EA's response, background, share activity)

SAN FRANCISCO/BANGALORE Dec 22 (Reuters) - Activision Blizzard Inc _(ATVI.O) wants to add archrival Electronic Arts Inc ERTS.O to a $400 million lawsuit related to its "Call of Duty" video game franchise.

In April, Activision countersued former executives Jason West and Vincent Zampella, saying that they tried to hijack the company's assets, threatening the future of "Call of Duty," a multi-billion dollar brand.

In a motion filed with California Superior Court for Los Angeles County on Tuesday, Activision sought to add EA as a defendant in the case against the two former executives, who developed the original "Call of Duty" game and several others in the series.

Activision's lawsuit was in response to the duo's lawsuit against the company, which challenged their dismissal and sought $36 million in royalty payments and damages. [ID:nN09123018]

The lawsuit seeks $400 million in actual and punitive damages from EA and the former executives.

The latest "Call of Duty" game, released in November, has already made more than $1 billion in sales. [ID:nN21257799]

In court filings on Tuesday, Activision said West and Zampella broke their long-term exclusive employment agreements to set up an independent company to develop games for EA.

After they were fired from Activision in March, West and Zampella formed a new development studio, Respawn Entertainment, and signed an exclusive publishing and distribution deal with EA. [ID:nN12202060]

Activision said that while West and Zampella were under contract with Activision, EA executives urged West and Zampella to meet with them, and enlisted intermediaries to help.

"As a result, Activision has suffered damages measured not in the millions, but hundreds of millions of dollars," Activision said in the filing.

EA called Activision's lawsuit "a PR play filled with pettiness and deliberate misdirection."

"Activision wants to hide the fact that they have no credible response to the claim of two artists who were fired and now just want to get paid for their work," EA spokesman Jeff Brown said in a statement.

Activision Blizzard is the world's largest stand-alone game publisher. Electronic Arts, which made its name on sports games, publishes titles like "FIFA 11" and "Need for Speed."

The case is Jason West v Activision Publishing, Superior Court of the State of California, No. 107041

Shares of Activision rose 2.7 percent to $12.57 in afternoon trading on the Nasdaq, while shares of EA rose 0.6 percent. (Reporting by Gabriel Madway in San Francisco and Sakthi Prasad in Bangalore. Editing by Derek Caney and Robert MacMillan)