Download here: http://freeloadstart.com/AnnamarieConaway341560/Hack
Thanks to narutoasdf and xX-_ALPHABET_-Xx to have let me know about that new cheat code ! I have no idea about who has originally found it out.
Written tutorial :
R2 + L2 several times at the main menu, until you stand up from the chair !
Then, go to the computer behind you, and press square.
Then, write manually that "3ARC UNLOCK"
Once you confirmed, it should say "Cheat enabled" and once you come back at the zombies menu, you should see every maps available.
ENJOY ! And Subscribe please. :)