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

Back then, 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 Pain. It launched on Early Access on Steam on February 2, 2021. It sold over one million units in just one week, reaching 160,000 top competing users and over 127,000 top Twitch viewers.