Okay, let me explain what the hell is going on here. One of the most pervasive legends of World War I is that in 1914 both sides called for an unofficial Christmas truce, with soldiers venturing onto the battlefield unarmed to meet the enemy, play football (the European kind), and just generally stop shooting each other and dying for a few days. It didn’t happen on every battlefield, nor did it ever really happen again. But for one moment, there was a sort-of lull in the Great War.
Verdun has recreated this unofficial truce for its winter event, with a map where you can throw snowballs at enemy soldiers, play football, and hang out with a big spike-helmet on your head without someone shooting it off. Also, write letters/emails to your loved ones from the trenches.
Apparently Verdun did this last year too, but given the game emerged from Early Access in May this is the first time I (and presumably others) am experiencing it. A big thanks to Rock, Paper, Shotgun for alerting me.