Dota 2 broke the 1 million mark for concurrent users this weekend — that figure means people signed in and playing the game at the same time — and is the first to do so in Steam history.
That's easily dwarfed by the numbers that League of Legends puts up — anywhere from 5 to 7.5 million concurrents according to numbers now two years old. Still, it's a significant milestone for Steam and is well more than double the No. 2 game's current player count (currently), which is Counter-Strike: Global Offensive at some 420,000 concurrent users.
Team Fortress 2 is a comparably distant third, with about 88,000 concurrents. Football Manager 2015 is the highest ranking non-Valve game, with about 71,000 concurrents.
Previously, Steam hit a peak of 8.5 million concurrent users — across all games — on Jan. 1.