Turns out that once you finish the story of Call of Duty: Black Ops 3, you unlock another version of it—one that’s not about futuristic cyber wars, but a zombie apocalypse.

It’s called “Nightmares” mode, and it takes the campaign levels of the original story and fills them with the undead. Turns out a virus was released in the late 20th century, creating billions of zombies, and you’re part of an elite group of soldiers called Deadkillers who fight them. It’s kind of a brilliant addition, as shown in the (very, very Metal) trailer above. Developer Treyarch turns things you did in the game’s main story into, literally, a nightmare.

Players familiar with the Black Ops games already know about their “Zombies” mode, in which a team of four people fights off waves of undead monsters, unlocking better guns and new portions of the game map as they go. Nightmares borrows some of the ideas, like finding better weapons and power ups somewhat randomly as you fight, but it runs with them in a completely different direction.

That’s a pretty cool bonus for Black Ops 3 players, especially if they like gunning down screaming, glowing-eyed undead. So, you know, all of them.