Steam purportedly has more than 250 million users worldwide, a large number of those having joined the platform in the past year as the monumental success of PlayerUnknown's Battlegrounds proliferated around the world -- especially China. This has lead in turn to a big increase in the number of concurrent players that Steam has had to handle and just a few days ago we hit a new peak: more than 18 million players online at once.
The holiday season is always a big time for gaming, as a larger proportion of the world's populations are home and have ready access to their PCs -- plus people tend to buy games for one another. That's why year on year early January tends to see new Steam records broken. In 2017 the new peak of 14.1 million was reached and in 2018 we're seeing the same sort of trend.
However, it's a bigger increase than most would have expected. With several new big games dominating on the platform, most notably PubG, Steam hit 18.5 million concurrent players on January 7. Many of those were in-game too, with almost 7.2 actually gaming away when that peak was reached.
Other titles that contributed to that big spike include old standouts like DotA 2 and CSGO, which continue to hold the number two and number three spots on the charts, while games like GTA V, Rainbow Six Siege and Warframe help top up the numbers.
Mostly though, Steam's numbers today come from the millions of gamers playing all sorts of titles right across the range at all times. Steam continues to be the biggest platform for gaming in the world and that shows no sign of changing in 2018.