

That's all there was to worry about, and going back to that formula for at least one installment would be great for longtime players. Kill zombies, build walls, and don't die. While one of the most popular elements of Call of Duty has been taken in all kinds of different directions by the Black Ops series, it was the simplicity of Nacht der Untoten that made Zombies a hit in the first place. And don't forget, Zombies originated in World at War.
