The information about this release is taken from the CDR database
Darkest Hour: Europe '44-'45, a DLC for the very successful Red Orchestra: Ostfront 41-45 FPS, will arrive on Steam for Linux.Darkest Hour: Europe '44-'45 DLC brings intense multiplayer action to the beaches of Normandy, Operation Market-Garden, the Battle of the Bulge, and on into the Reich.
Players will get access to a multitude of new weapons, new infantry features, a dozen new crewable vehicles, and 11 new maps. The DLC is free and available to everyone who already has Red Orchestra: Ostfront 41-45 on Steam for Linux.
The other part of this information, about the Linux port, is taken from the CDR database and by no means is it completely certain. The CDR Database is a record of data that describes every Steam game and subscription provided by Valve for the Steam service.
Usually, the new entries in the Steam database are first visible in the CDR Database before their official launch.