Fallout 4 previously held Steam's record for most players in a singleplayer game, with 472,962 people playing Bethesda's open-world game at launch in 2015. Today, Cyberpunk 2077 (opens in new tab) blew right past that and kept going, with 1,000,297 concurrent players at the time of writing [Update: It peaked at 1,003,264, and is now drifting back down]. Of course, with CD Projekt's new RPG available on GOG, Epic, GeForce Now, and Stadia as well as consoles, the true number of people exploring Night City at the moment (or at least, trying to) is even higher. There are a million people watching it on Twitch (opens in new tab) too.
The current overall record for the most players in a game on Steam was set by PUBG, with 3,257,248 people simultaneously chasing a chicken dinner on January 13, 2018. But Cyberpunk 2077 has already surpassed Terraria's peak of 489,886 and is catching up on Dota 2 (1,295,114 players) and CS:GO (1,308,963 players).
By the way, if you're still looking at Steam's download speeds in despair right now, it might just be that servers are overloaded in your locality. Go to Steam>Settings>Downloads and switch your download region to somewhere on the other side of the world. You're welcome.
And while you're waiting for that download to complete, here are 8 things you absolutely should not miss in Cyberpunk 2077 (opens in new tab) and an atmospheric tour of Night City to watch (opens in new tab).