PlayerUnknown's Battlegrounds has had quite the successful launch in Early Access, selling over four million copies in its first three months and attracting enough players to keep it firmly wedged into the number three spot on Steam's Top Games list by playercount. The only games above it regularly have been Dota 2, Counter-Strike: Global Offensive, and Payday 2 (the last of which gave away five million free copies last month, rocketing it up the list—it currently sits at number seven).
Brendan Greene, aka PlayerUnknown, tweeted earlier that PUBG had climbed to number two on Steam's Top Games list—albeit briefly—marking the first time Bluehole's Early Access battle royale shooter has had more concurrent players than CS:GO, with just over 239,000 (whereas CSGO, at the time, had 238,742).
For a brief moment tonight, @PUBATTLEGROUNDS had more players online than @csgo_dev! Thank you one and all July 9, 2017
PUBG doesn't look like it held onto second place for very long, and currently I'm seeing some 500K CS:GO players on Steam's stats page, pushing the battle royale shooter back down to number three. It's still quite an accomplishment for Battlegrounds. Though Greene also recently announced that PUBG will be spending a bit more time in Early Access than originally planned, players still seem to be flocking to it in droves.