Uncharted 4 is getting an all new co-op mode, Survival, in mid-December.
As detailed on the PlayStation Blog, this standalone mode tasks up to three players to fend off increasingly powerful waves of enemies. Spread across 10 maps, each challenge will consist of 50 waves of foes with a boss appearing every 10th wave. You can catch a glimpse of the Djinn-wielding Warlord boss in the trailer below.
There's more to Survival mode than just slaying enemies though, as you'll be given more varied objectives like collecting a certain amount of treasure within a time limit, or defeating marked foes. Sometimes you'll be given more stringent rules, like waves where you can only use pistols, or you'll face off against enemies that only take damage when shot in the head.
As you complete objectives you'll earn cash to upgrade your gear throughout the trial. There will also be a dedicated long-term progression system so you can customise your loadout.
Survival will have multiple difficulty levels available with the ultra-hard Crushing setting available to those who complete Hard mode.
While Survival is designed around co-op play, it will also be available as a single-player experience.