Treyarch has a ton of mysteries in zombies we all understand the story up until moon the four characters are attempting to get to the moon with the golden rod so Richtofen can take control of the MPD machine. Once they get to the moon and you do the easter egg Richtofen and Samantha switch places and Maxis gets Tank, Nikolai, Takeo and Samantha to destroy earth to end the outbreak but it only damages Richtofen's link to earth and Richtofen can't properly control the zombies. I've heard after moon the original three die and the green run characters are introduced in Tranzit they follow the steps to the easter egg either doing Maxis' side or Richtofen's either way Richtofen teleports them into Die Rise after doing the next easter egg the four are teleported to Buried where Richtofen wants them to mend the rift to fix his link so he can overthrow Maxis. Or if you do Maxis' end Maxis wants to close the rift and overthrow Richtofen. Either way Maxis takes Samantha's soul (from Richtofen on the moon) into Argartha thus starting Origins Samantha searches Argartha for an alternate version of her father and finds him in Origins so she goes back in time to 1917 and the origins characters must free her from Argartha. Basically after Moon we never hear from the original crew from W@W until Black ops 3 when the story gets more confusing and the origins characters have to go around and kill theirselves from the original W@W timeline.