Zynga, the online game developer that made Facebook a safe haven for desk-bound farmers and wannabe Mafia hit men, has decided to cash in on all the fun with an initial public offering filing Friday that expects to raise $1 billion.

Zynga’s S-1 SEC filing begins with a chatty, casual appeal from founder and CEO Mark Pincus: “At Zynga, we feel a personal connection to our games through our friends and family. I love that my brother-in-law, who has five kids and no free time, religiously plays our game Words with Friends.”

But the filing also confirms that it is not all fun and games at the 4-year-old company, which has 2,000 employees and boasts 60 million daily active users. There’s a big differentiator from some other red-hot tech IPOs that have exploded in value on their first day of trading in 2011.

They make money. About $90 million on revenues of nearly $600 million last year.

Zynga hopes to raise as much as $2 billion in a public debut that could value it at as much as $20 billion, “people close to the deal” told the Wall Street Journal. This probably will not be a game of chance for Zynga, what the prevailing “What dot-com bust?” attitude on Wall Street for internet, tech and similar IPOs.

The past few months have seen more high tech activity and questionable frenzy on the Street than in the nearly decade since the bust at the turn of the millenium. One notable exception is Google, which IPO’d in 2004, remains the most successful public internet company ever — and has a stake of $100 million to $200 million in Zynga.

LinkedIn, which earned $15.4 million on $243 million in revenue last year, more than doubled on its first day last month — and is trading well above that level now. Pretty much the same story at ZipCar, which is at its launch-day levels and Demand Media, which has dropped — neither of which have made any money. Groupon filed its S-1 earlier this month and hopes to about $750 million in an IPO that would value the company at $15 billion. The coupon company lost $450 million on sales of $644 million last year. Facebook, the 800-pound gorilla, is widely expected to IPO next year at a valuation that — OK, let’s just admit we all just want to repeat the craziest high estimate — could tip the scales at $100 billion and it makes about 1/100th of that.

Investors may also take into consideration that for the addicted Zynga games are guilty pleasures — and those are the best kind. According to AppData, the company has more monthly active users on Facebook than the next 16 social game developers combined.

Image: Zynga’s S-1 filing.