If you’re a PC gamer, chances are you use Steam. It’s the biggest gaming platform on PC, with an estimated 75% market share in 2013. It’s only grown since then, and I’m sure its market share hasn’t particularly shifted by much either. I’d argue that Steam is a monopoly (or at least an oligopoly), and I wouldn’t be the first to do so either. There’s a stark lack of competition in the PC game distribution space, and Valve is basically the only provider for most games that are released on PC.