Although it's tight-lipped about its financials, leaving analysts and media pundits to make all kinds of wild guesses, there's no doubt that Valve is doing very, very well, thanks largely to Steam, which owns the vast majority of the PC gaming digital download market.
With 250 employees, founder Gabe Newell tells Forbes Magazine that the company is "tremendously profitable" -- more profitable per employee than Google and Apple.
He won't confirm reports that other companies have tried to acquire either Valve as a whole or Steam separately, but admits there's been interest.
Being quick to market with Steam, which gave PC gamers a simple one-stop online community for buying, downloading, authenticating and patching games, is one component of the company's success.
Developing highly-regarded games like Half-Life, Left 4 Dead, Team Fortress 2, Portal and Counter-Strike, and encouraging a thriving mod community are Valve's other keys to success.
Valve also offers a Steamworks tool suite for developers to implement certain features in their PC games, like matchmaking, beta-testing, metrics tracking and other tools for developers.
Although it's released games on Mac and console platforms as well as PC, Valve's managed to attain its profitability by remaining focused primarily on the PC gaming market, which is less than 10 percent of the overall gaming industry.
But it's that very focus that helps drive the company's success, Newell tells Forbes: "If we tried to blaze new trails of our own and ride all the latest trends, we'd likely be bankrupt by now."