Zynga, the biggest games maker on Facebook platform, filed for an initial public offering (IPO) on Friday that could lead to upwards of $1 billion from investors.

Some of its biggest hits include FarmVille, CityVille, and Zynga Poker. The company makes money through advertising and by selling virtual level-ups or gifts Facebook gamers can present to their friends.

The main point is how much of Zynga's business is directly dependent on Facebook.

While the SEC filing did not get into details regarding the offering-price or the range of shares to be offered, it highlights the company's near-dependence on social-network Facebook.

Zynga generates substantially all of [its] revenue and players through the Facebook platform and expects to continue to do so for the foreseeable future, Zynga says.

Much of this is through the sale of virtual goods using Facebook's credit payment system, of which Facebook retains a 30 percent cut.

Zynga is the most successful company based on Facebook platform. Regardless of how well the Zynga team itself performs from this point forward, Zynga's financial success will undoubtedly be tied to that of Facebook and social networking.

The relationship is working well for Zygna for now. However, any change to Facebook’s policies could harm Zynga, which is locked into a partnership with Facebook until May 2015.

Facebook has repeatedly changed the terms on its relationships with developers, including Zynga.

Last year Facebook began requiring game developers to use its credit system, in which Facebook wanted to take a 30 percent cut of transactions over the currency. Zynga says this change has harmed its earnings.

If Facebook gets obliterated by Google+, Zynga's going to tank. If Facebook continues to grow at a blistering pace, Zynga's going to benefit.

The social gaming giant saw revenue surge nearly 400 percent to $597.5 million in 2010 and reported a net profit of $90.6 million for the year.

Earnings for the first quarter of the current fiscal were $11.8 million on revenue of $235.4 million - putting the company on track to surpass the $1 billion mark in revenue this year.