According to a new survey conducted by Steam Spy, the three most popular games for Steam users are Dota 2, Counter-Strike: Global Offensive, and Team Fortress 2. This lists the rankings of each game according to total time spent playing.
Steam Spy was created by Sergey Galyonkin who developed the web API to collect information about gamers “and all parties interested in PC gaming and its current state of affairs.” However, he admits that the API, “extrapolates data from a limited number of user profiles and thus isn’t 100% correct.”
He goes on to say that, “So 0.1% margin of error for a game with 0.1% of Steam audience would produce results that are mostly useless. That’s why Steam Spy has to gather millions points of data daily to predict games sales and audience. And that’s why Steam Spy is often wrong. Not by much, but still wrong.”
In March 2015, Steam hit its all-time record of 9 million concurrent users. Dota 2 led the pack with around 900,000 concurrent users, followed by 600,000 for Counter-Strike: Global Offensive.