Nearly seven years after release (or eight years after its Early Access release), Darkest Dungeon has been bought 6 million times. And if we also take into account the additions, then the total sales are 16 million copies.
Red Hook Studio last reported about the sales of the game in September 2021. Then the asset Darkest Dungeon was 5 million copies.
Darkest Dungeon is available on PC (Steam, Epic Games Store, GOG, Microsoft Store), PlayStation, Xbox, Nintendo Switch, PS Vita, and iOS mobile devices.
Recall that Darkest Dungeon II has long appeared in the early access of the Epic Games Store. A full release will take place in February 2023, including on Steam. Console versions will be, but sometime later.