Valve

Privately-held Valve Corporation is tight-lipped about revenues, and Newell doesn't comment on his personal finances. So in order to estimate his net worth, Forbes consulted with video game industry insiders, equity analysts, investment bankers, and technology analysts to figure out what the company is worth. Even the most conservative estimates put Valve's enterprise value at more than $3 billion, and since Newell owns more than 50% of the company, that means he's worth at least $1.5 billion.

Gamepro editor John Davison explores the truth that Valve revealed to us years ago: video games are too long and too hard. Most people don't even complete them. A great quote from this article: "we're not playing it wrong. What's happening is that studios are starting to look at the way they make games and concede that they're making them wrong"