Rebellion has announced The Red Strain, a brand new DLC expansion for Atomfall that's launching next month, although the studio is keeping its cards close to its chest regarding what you can expect for now.
The Red Strain was announced earlier today via a brand new teaser trailer, and "teaser" really is the word; the trailer reveals the name of the expansion, as well as a C.O.R.E. robot standing in front of some kind of red growth (presumably the Red Strain of the title).
What we do know is that this will be Atomfall's second major story expansion, following on from June's Wicked Isle, which introduced a brand new area and other goodies to Rebellion's open-ended shooter.

While Rebellion hasn't revealed exactly what will be introduced as part of The Red Strain, the studio does say you can expect "a highly confidential new location", as well as "plenty more mysteries to uncover". That sounds about right for an Atomfall expansion.
If you're not familiar with Atomfall itself, it's an open-ended first-person shooter developed by Sniper Elite and Zombie Army studio Rebellion. It's set in a 1960s England that was a lot more heavily impacted by the Windscale nuclear disaster than the one in real life was.
At the outset of Atomfall, you awaken in a bunker with amnesia, and it's up to you to explore the Windscale plant and its surroundings in order to discover the truth behind Windscale and why a mysterious voice is telling you that a being known as Oberon "must die".
Somewhat unusually for modern games, Atomfall essentially allows you freedom in how you pursue your objectives; you'll have several leads to follow at any given time, and the order in which you chase those leads is largely up to you.
Atomfall is available right now on PC, PlayStation, and Xbox, and it's also a day one Game Pass title. You can read our very own Erren's review of the game to find out what she thought of it right here.