Battle royale is a pretty fluid and flexible game mode since the concept of a bunch of players fighting to be the last one standing can fit into just about any kind of multiplayer game. So maybe it's not all that shocking that yes, even Civilization 6 is getting a battle royale mode. And it's got nukes!
Civilzation 6: Red Death is out today, free for any current owners of Civ 6. Red Death supports up to 12 players per match, though there are a number of map sizes suitable for smaller groups, including two-player duels. You can also play against AI-controlled opponents.
You don't build civilizations in Civ 6's battle royale: it's far too late for that. Red Death takes place in the post-apocalypse where cities are ruins, the landscape is lifeless, the oceans are acid, and a radioactive storm—the Red Death—is slowly closing in from all sides. It's probably Gandhi's fault.
Rather than build a civ, you manage a post-apocalyptic faction comprised of mobile combat units protecting a civilian unit—and if that civilian unit dies or is captured, you're out of the match. You explore the map with your units, a turn at a time, hoping to gather additional units and level them up with XP. Meanwhile, the Red Death closes around you, forcing you into contact with other players and AI-controlled enemies and outposts in the ever-shrinking safe zone.
Six of us played a match of Red Death last week, and I've played a few more times against the AI. You can read all about it here.