Some fans may not realize this, but Call of Duty: WW2 actually has two Nazi Zombies map. The main map is The Final Reich, complete with an elaborate Easter Egg, and the second map is called Groesten Haus. In Call of Duty: WW2, Groesten Haus is the map players play in the Nazi Zombies Prologue, but it can also be unlocked for online play.
To unlock the Groesten Haus Nazi Zombies map in Call of Duty: WW2, players need to complete the “casual” Easter Egg on The Final Reich map. For those that don’t want to go through the trouble of completing the rather complicated Easter Egg, the map is automatically unlocked for local play.
For the most part, Groesten Haus is a simple map. It’s small, the perks are all located on one machine, and there aren’t any insane Easter Egg steps to complete. However, there is at least one secret on the map, and completing it will grant players access to the mystery box located in the room upstairs.
As seen in the video, unlocking the mystery box in Groesten Haus is a matter of shooting 10 lanterns that are hidden throughout the map. Eight of these lanterns are located in the house itself, though two can only be found outside by looking through windows. There are four lanterns upstairs and four downstairs, so players can easily keep track of which ones they’ve shot and which ones have yet to be activated.
Once all 10 lanterns have been shot, the door to the mystery box will open. Just like in The Final Reich map, the mystery box costs 1,000 Jolts and will grant players a random weapon. However, the Groesten Haus mystery box is special in that it never disappears, meaning players can use it indefinitely.
While players don’t have to use the mystery box in Groesten Haus, doing so makes it much easier to survive on the map, especially in the higher rounds. Anyone going for the Pressure Cooker achievement/trophy (which is for surviving at least 20 rounds on this map), will definitely want to make sure that they hit the mystery box a few times to help them with slaughtering the undead masses.