Nobody ever releases digital sales numbers on PC. Least of all Valve. Still, that hasn't stopped Ars Technica from rolling up their sleeves and getting the data themselves.
Trawling through thousands upon thousands of public profiles to gain user data, they have compiled a list that, minuscule margins of error aside, gives us our first ever look at what the most popular games are on Steam, how many people own them and how many games they're actually playing.
You need to go read the whole thing, because it's fascinating. Sure, DOTA 2 dominates many categories in raw numbers, but it's free and it's a little misleading. You'll find that Football Manager and Civ V are right up there in terms of time wasted/marriages threatened.
The most reassuring thing the study finds is that a lot of people are buying games they don't play, whether during sales, as part of bundles, or both. Take a look below, and if you're part of that 36.9%, know you're not alone.