Easter egg?

[Dannymoe70]

So i was looking fir tips, instructions in how to do the estrr egg on this map.

 

I can get the skulls, zombie shield, KT-4, gas mask, pack a punch, windows wine.

 

What is the easter egg?

How do I start it?

is it hard?  

Any tips I may need to complete it?

 

 

[Hells Warrrior]

Have a look here, as an XBox One player, I haven't looked at the ZNS forum section. Going into the game dark, played it on the PS4 a couple of times but nothing major and I decided to wait until the 19th.