'Farmville' maker Zynga Inc said it has acquired Texas-based mobile game development company Newtoy, Inc. for undisclosed terms to boost its social gaming portfolio.

Founded in 2008 by brothers Paul and David Bettner, alongside chief operating officer Michael Chow, Newtoy has developed some of the most popular mobile social games such as Words With Friends and Chess With Friends.

Newtoy's Games With Friends franchise is the most popular gaming platform on the iPhone, iPod Touch, and iPad, with millions of monthly active users playing more than an hour each day.

The Games With Friends franchise is the best social game experience available on mobile today and we are excited to welcome the Newtoy team to the Zynga family, said Mark Pincus, founder and CEO of Zynga. The Zynga With Friends Studio will continue to invent great mobile social game experiences for Zynga users everywhere.

The Newtoy headquarters in McKinney, Texas will become The Zynga With Friends Studio, a new game studio that leverages the popular franchise and builds new games for the Zynga network.

Newtoy CEO and co-founder Paul Bettner immediately will become Vice President and GM of The Zynga With Friends Studio, reporting to David Ko, senior vice president of mobile at Zynga.

Bettner will lead the team to develop new mobile social games for the Zynga network that leverage the company's rich experience and creative game development environment.

We're reinventing the way people are social on their mobile devices, said Paul Bettner, VP and GM of The Zynga With Friends Studio. The Zynga With Friends Studio will build on the Newtoy legacy of creating approachable, highly social games that are accessible to anyone from anywhere.

Zynga, whose games are also available on MySpace, the iPad and the iPhone, is the world's largest social game developer with more than 225 million monthly active users playing their games. Zynga's games include FarmVille, FrontierVille, Mafia Wars, Zynga Poker and FishVille. Zynga's Farmville has more than 80 million users.

Zynga, which is reportedly worth more than $5 billion only three years after it was founded, is said to be generating revenue between $500 million and $700 million a year and many analysts expect the company to pursue an initial public offering as early as next year.

San Francisco-based Zynga recently released its Mafia Wars and FishVille games onto the Yahoo! platform. Zynga's most popular game, FarmVille, recently launched on both the iPhone and the iPad and Zynga Poker will be the first Zynga game launched on Android. The company also recently announced its next game, CityVille, which is available now on Facebook in French, Italian, German, Spanish and English.