The Iron Gate Studio title achieved this feat in less than two weeks
In just 13 days, the procedurally generated Viking survival game Valheim sold more than two million copies.
During that time, the Iron Gate Studio title reached a maximum of 360,000 simultaneous players, the studio added.
However, it seems that this record has already been broken. At the time of writing, Steam Database was showing a maximum of 392,862 players for the game.

At the time, Valheim was the fourth most played game on Steam, behind Counter-Strike: Global Offensive, Dota 2 and PlayerUnknown’s Battlegrounds.
Valheim was made by a very small team of five people and is published by Coffee Stain. It was launched on Early Access on Steam on February 2, 2021. It sold over a million units in just one week, reaching 160,000 maximum concurrent users and over 127,000 Twitch viewers.