Game Idea - Cod Zombies RPG FPS

Imagine an open world game based around the complete nazi zombie storyline. The only way i can see this work is by having a borderlands type experience, in which you can play up with a maximum of 4 players. You would buy weapons from vendors or rare buys, level up and also train your skills (perks).

Perhaps in your character creation, you can build your character around specializing in 4 skills(perks) and you can gain more skills by completing full on easter eggs.

The entire world map can consist of all of the past maps, linked to a fast travel system we are familiar with, the teleporters! The introduction area can be Der Riese, where they could introduce the prologue right there. The first quest/mission would be to open up pack a punch, in which it would enable the ability to fast travel to a variety of maps (probably shi no numa and verruckt as first locations to travel to).

Possible questions you might have:

• How would the round system/zombie health and quantity work?

I believe this would all be location based, for example the first area would spawn zombies at a mild rate as well as having low health. But in contrast, later locations like moon would feel like being on round 40+.

• How would you get wonder weapons?

Completing scripted/hidden easter eggs I'd reckon.

Do you guys like my idea? It's only a dream.