Call of Duty: Black Ops

Black Ops is where Zombies became a full pillar of the game rather than a bonus. It shipped with Kino der Toten and the Pentagon map "Five" — plus the top-down Dead Ops Arcade — then ran a DLC arc that reads like a serialised story: Ascension’s cosmodrome, the celebrity-crewed Call of the Dead, Shangri-La, and finally Moon, where Richtofen’s scheme comes due and the missiles fall on Earth.

This is the era that invented the co-op main quest. Ascension’s Casimir Mechanism was the first true multi-step group Easter egg, and each map after it escalated the format; it is also the era of the Thundergun, the Gersch Device, and perk debuts like PhD Flopper, Stamin-Up, Deadshot Daiquiri and Mule Kick. Every map here except "Five" was later remastered in Zombies Chronicles.