The old-school RTS Grey Goo has added a fourth faction by way of the Descent of the Shroud expansion that went live today. The Shroud are a destructive alien life form who have come to Ecosystem 09 to feed off its energy, and destroy the Human, Beta, and Goo forces that are already there.
The Shroud's units “look and behave differently” than those of the other factions, with a focus on stealth and deception. The Mimic, for instance, will change appearance to blend in with, and spy on, enemy forces, while the Klaxon looks like a slow-moving armored unit but can “charge at and damage your units in a split-second.” Shroud units and structures also have the ability to evolve on the fly; the first of the Dirge's three stages is relatively weak, but “its final form can end a game in a matter of minutes.”
Descent of the Shroud actually went live just a couple of hours ago—1 pm EST, to be precise—and it's free for everyone who already owns Grey Goo. For those who don't, it's also available as part of the newly (and permanently) discounted Grey Goo Definitive Edition, which includes the base game, the Emergence campaign, and the soundtrack, for $30/£23. The Definitive Edition also adds three new units—the Human Valiant, the Beta Squall, and the Goo Siphon—a new “Herald of Silence” mission, new Shroud-related achievements, and “an extensive gameplay balance overhaul.”