Facebook game developer Zynga is confident investors haven’t tired of tech companies, despite the highly publicised IPOs of LinkedIn and Groupon.

Zynga and its bankers have set the company’s IPO price at the upper end of the expected range of between US$8.50 and US$10. With 100 million shares on offer, plus 15 million over-allotment shares for underwriters, the company stands to raise over US$1 billion, giving it a market value of US$7 billion.

The company certainly has a history of creating engaging content, from the ‘ville’ titles Castleville, Cityville and the ubiquitous Farmville to Zynga Poker, Mafia Wars and Words With Friends, the scrabble-inspired game made famous by Alec Baldwin.

With its games available for free, Zynga turns a profit by having a huge user base, and encouraging each user to make tiny purchases to enhance their experience.

The concern among investors is that the company’s success is so intimately tied to that of Facebook. Over 90% of Zynga’s profit is generated through Facebook, which takes 30% of every dollar spent on outside applications.

It’s a model that’s served the game company well so far, but if anything were to go sour Zynga could struggle. There are already plenty of people who are infuriated by their friends sending notifications inviting them to join the fun; as with all tech stocks, the potential for users to just up and leave is ever-present.