"Where the hell did everybody go? Aw, dammit! No matter how hard I wanted to believe, deep down I just knew Richtofen was going to fuck everything up! Giant monsters in the sky, islands in space? It looks like someone put the entire universe in a massive blender and pressed start! Suppose I try to find this Doctor Monty. Pretty sure he's on the right side of the fight. Aw geez, where do I start?"
Not the best quote you could've picked, but I love the zombies mode in all of the Treyarch Call of Duty games. I haven't played as much in Black Ops 4, but in Black Ops 3 I did every easter egg, hit level 740, had about 23 days logged, and got to round 150ish on Ascension without power.