Call of Duty Black Ops comes packed with new zombie adventure along with 1 map “Kno Der Toten” and two other maps are greyed out and labeled “Classified”. Below is a guide on How to unlock the two maps along with a Dead Ops Arcade game.
On PC, PS3 or Xbox only!
Step 1: Go to Main Menu
Step 3: Using right analog stick, look around.
Step 4: Looking at your hands, press L2, R2 quickly repeatedly.
Step 5: Mason should get up
Step 6: Move around and go behind the chair
Step 7: You will see a Computer, on PS3, Hold square to sit on it.
Step 8: Type “3Arc unlock” and hit enter.
Step 9: It should say “Cheat Enabled”
Step 10: Press X and go to zombie mode and under maps all three maps should be activated!
If need visual check out the video below: