Go to the Datavault in the Safehouse in the Single Player Campaign. In the screen where you unlock Dead Ops 2 (Top left corner in the menu) press Left Trigger, Right Trigger, X and Y to unlock a hidden Menu where you can enter Codes.
| Code | Effect
|
|---|
| Dreamland | Unlocks Nightmare Mode straight away.
|
| Manifest | Get 60-100 Fabrication Kits.
|
