Call of Duty Zombies Jumpchain

From the introduction: The world you are about to enter... is my world. It’s a bit of a mess right now, what with all the undead and eldritch abominations running around. I do what I can for this place, but with all my other interdimensional duties, and with how utterly fucked it is, I can only do so much. That’s where you come in. You’re gonna fix things! I hope. Please. It’s difficult on my own.