Since Call of Duty: World at War, special modes featuring the undead have been one of Treyarch's trademarks. It looks likes zombies will be back in Black Ops II.
Today, the official Call of Duty Twitter account tweeted the above teaser image, in which the word "ZOMBIES" is scrawled over a sign for the fictional berg of Nuketown. This seems to indicate that there will be zombie mode(s) in Black Ops II. Which, given the popular of past zombie modes in Treyarch games, should surprise exactly no one.