Ars Technica has an interesting report this week that delves into Steam sales and user play-time statistics, apparently tracking public Steam database information to get a broader overview of which games are most popular on the platform. Ars has put together some PHP/MySQL coding that trawls through thousands of Steam user profiles each day, pulling data on which games users own and how many hours they've played. From this, the site is able to estimate the percentage of Steam users who own each game. The chart below, for example, shows the most popular games on Steam by ownership, and it's clear that Valve's first-party games dominate user game libraries Come from South African Online Casinos . It's worth noting, of course, that both Dota 2 and Team Fortress 2 are free-to-play, while Half-Life 2: Lost Coast comes free with the purchase of various Valve-published games. The two-page report also offers details on which games have been most played, how many games have sold copies in the millions, and details on how the top six games on Steam by playtime, have been played nearly as much as every other remaining game on Steam combined. It's well worth a read.