(Image credit: Valve) Steam is, by a country mile, the premier power in PC gaming. If you own a PC and play games on it, then it's just about a guarantee you use Steam with some regularity. You might therefore expect that, like Sony with PlayStation and Microsoft with Xbox, Valve would feel obligated to promote and support the PC. But 15 years ago, when Steam was still relatively youthful, Gabe Newell said that's not quite the approach he takes. "It's a lot easier for me to think of it as having a responsibility to gamers and game developers," the Valve boss told us back in 2011 . "It's hard to test being the flagbearer for the PC. It's a lot easier to go out to customers and find out, 'Do you like this? What do you dislike about this?…