To unlock extra modes in Wolfenstein: The New Order, you need to search high and low to find the secret Enigma codes that are scattered about. Each set of codes contains 18 numbers, and there are 4 different codes to solve altogether. Sound a little daunting? Nothing is too tough for a freedom fighter like yourself, especially when you have the locations of each piece of the code like you do here!
Looking for more help? We also have a Wolfenstein: The New Order letters, gold, and health locations guide.