ZombiU

Game Cheats:

Keypad Code Buckingham Palace:
The keypad code at Buckingham Palace is 4324, this can be found written in blood on the wall next to the keypad.

Letter of Dee Victoria's Memorial Location:
In the room at Victoria's Memorial where you get C4 you will find a dead body slumped against the wall. Loot this body to find the letter (don't bother zombifying the body).