The total market for virtual games is estimated to be a billion dollars in the U.S. alone. Some experts say it could be as much as five billion by 2013 while right now in Asia the market is already about that figure.

Critics have raised concerns that not everything is conducted in an orderly fashion in the world of online gaming. There have been suggestions that Zynga's partners have engaged in dubious business practices. They offered Farmville users money in exchange for purchases of software and mobile phone ringtones.

One of Zynga's critics is the information technology blog TechCrunch. The blog's founder Michael Arrington thought Farmville's money-for-software deal was a subscription trap and created the term “ScamVille” to describe it. Zynga called a halt to the practice but in the meantime a class action suit is working its way through the American courts.

Another aspect of concern is data protection. If you join Farmville you automatically allow Zynga access to your profile, photos and information about friends. “The privacy policy is very unclear and Zynga reserves the right to gain access to just about everything,” says Henry Krasemann from an independent data protection body in Germany, the Landeszentrum fuer Datenschutz Schleswig- Holstein.

Zynga creates profiles on its users that are made up of information from several sources such as “newspapers and internet sources such as blogs, instant message services, Zynga games and other users of Zynga,” as the company's webpage explains.

Together with information provided by the user's browser as to what sites he or she has visited, Zynga uses that data to create targeted advertisements. According to German law that is a grey area, possibly even improper, according to Krasemann. Zynga's policy of storing data on users permanently is also a cause of concern for German data protectionists.

Anna Tschochner, a 25-year-old from Munich, was a busy and hardworking farmer in the beginning. Many of her Facebook friends joined Farmville, thanks in part to her Facebook page which was littered with status and activity updates from Zynga, and Tschochner thought it was a pleasant way of passing the time.

Then Zynga withdrew money from her PayPal account on three occasions although she never gave the company permission to do so. Tschochner has now warned her Facebook friends. She received her money back but her enthusiasm for Farmville has withered on the vine.