In PC gaming, online stores have largely replaced retail. The major ones have their own software packages that manage downloads, instant messaging, and the actual shopping experience. Steam is the king of the hill, at least in terms of sheer popularity. But Ubisoft and Electronic Arts have created their own versions of it, complete with franchises like Battlefield and Assassin’s Creed that can only be accessed through their walled gardens. So, let’s determine who’s No. 2 around here.