On the Xbox 360, "Minecraft" has sold more than 12 million copies, just 2.5 million short of the total that "Halo 3" managed to sell (despite that game's five-year head start). Despite its age, "Minecraft" is regularly among the 10 top console sellers each month, according to The NPD Group.
Mobile is a potential growth area for the game, as well. "Minecraft" is one of the top grossing games in Apple's App store, but Mojang has refused, so far, to create a Windows Phone version, because of that product's low sales, a decision that will likely be reversed in the coming months.
Still, while Mojang and Microsoft have been partners for a long time, the relationship hasn't always been a smooth one.
Marcus "Notch" Persson, co-founder of Mojang, has repeatedly criticized the company. He has publicly pointed out the weaknesses of the Windows Phone division several times.
And, in 2012, he tweeted that he had "rather have 'Minecraft' not run on Win 8 at all than play along. Maybe we can convince a few people not to switch to Win 8 that way...."
For Persson, though, the Microsoft deal lets him escape the high-profile industry role he never actively sought, he says.
"I've become a symbol," he said on his website when the deal was announced. "I don't want to be a symbol, responsible for something huge that I don't understand, that I don't want to work on, that keeps coming back to me. I'm not an entrepreneur. I'm not a CEO. I'm a nerdy computer programmer who likes to have opinions on Twitter," he said.
"As soon as this deal is finalized, I will leave Mojang and go back to doing...small web experiments. If I ever accidentally make something that seems to gain traction, I'll probably abandon it immediately.... It's not about the money. It's about my sanity."
—By CNBC's Chris Morris.