Online social gaming is set for rapid expansion as the company behind the Facebook favourite, FarmVille, has announced plans to bring its games to more people.

Zynga has launched a new Facebook game, FrontierVille, which will join a growing list of money-spinners.

FarmVille, a cartoon-like universe in which players build and maintain farms, rear livestock and tend crops, is played by about 70million people a month.

Such games are one of the main factors driving the growth of social networking sites, particularly Facebook, on which 90% of all "social" games are played. Facebook has almost 500 million users.

Zynga's latest game is a Wild West-themed social game that allows users to tame the wilderness, raise a family, and build a thriving frontier town. FrontierVille's debut comes on the heels of the recently launched Treasure Isle, which became the fastest-growing Facebookapplication and one of Zynga's most popular games, with 25 million daily users.

Billed as "Oregon Trail meets Little House on the Prairie meets FarmVille", FrontierVille is being heralded as the leader in a new generation of social games as a result of its introduction of features such as the ability to hire friends to work your land. And for the first time - in an attempt to broaden its appeal to female gamers - Zynga is allowing players to "customise" a spouse and raise a virtual family.

"FrontierVille gives users creative new ways to connect with people around the world while bringing out the pioneering spirit in all of us," says Brian Reynolds, the game's general manager.

Though FrontierVille and other Zynga games can be played for free, they generate revenue by encouraging players to buy virtual items to improve their creations - with real cash. Zynga, which launched its first game in 2007, has an estimated annual revenue of $150-million (R1.1-billion).

Zynga has led the online gaming revolution, with companies such as Playfish and Playdom also attracting millions of casual gamers to Facebook and other sites.

The company, based in San Francisco, has expanded rapidly and has more than 900 employees. It recently announced the acquisitions of XPD Media and Challenge Games, establishing new Zynga game studios in Beijing and Austin, Texas.

Zynga has signed a deal with Yahoo! that will, by the end of the year, allow games such as FarmVille and Mafia Wars to be played on Yahoo! sites, including its homepage and Yahoo! Mail. This gives Zynga the chance to reach a potential new audience of 600million people worldwide.

A version of FarmVille has just been released for the iPhone, and the company has signed a five-year partnership with Facebook that will keep its games on the world's most popular social network, quelling rumours of a break-up. - © The Sunday Times, London