From GameWatcher: “Ready for some Infested Mines? Some time has passed by since Space Hulk: Deathwing was launched, and Streum On Studio, the developers, have been hard at work polishing up the game’s performance on both PC and consoles, as well as fixing bugs and other assorted issues as they popped up.”
Source: N4G PC Space Hulk: Deathwing Getting a Batch Of Free Content – Infested Mines Update