One of the most popular (but smallest) maps in the first Call of Duty: Black Ops was Nuketown. The tiny map allowed for maximum death tolls, making it an awesome map to play (and die) on. In the latest Call of Duty: Black Ops 2, that map returns in the form of Nuketown 2025, a futuristic version of the same level.
It was available for free on November 13th to anyone who pre-ordered the game, purchased a launch copy, or purchased the Hardened or Care Package special editions of the game, though, for some strange reason, it was pulled by Treyarch (Activision) and soon re-added to the Chaos Moshpit playlist.
In Black Ops 2's Nuketown 2025, there's a cool Easter egg that allows you do play an Atari right in the map, giving you invincibility while playing the old gaming system.
In order to unlock this, you will need to shoot all of the mannequins on the level headshot-style. This should be done in less than 2 minutes.
To speed up the process, you can enlist the help of a friend to decapitate all of those mannequins.