It could only happen on PC: Garry's Mod , a seemingly pointless sandbox allowing all manner of ridiculous and perverse experimentation, has managed to sell 6 million copies. The news comes via Garry Newman himself, who managed to drag himself away from mountains of cold hard cash for long enough to Tweet the news.
Garry's Mod originated as a Half-Life 2 mod. It hit Steam in 2006 and, according to figures from April 2013 , has earned over $22 million. More than a year later, and since the game went standalone earlier this year, that figure has no doubt increased significantly. As reference, the game had sold a mere one million copies back in 2011.
Along with the new sales milestone Newman provided a platform breakdown for the title. The vast majority sold for Windows, 336,765 sold for Mac and 28,322 for Linux.