User blog comment:Damac1214/Thoughts on the Black Ops 2 Zombies series/@comment-9645468-20130707184403/@comment-1187559-20130708124713

When Zombies was first made it was just a laugh, they didn't think it would as popular as it was, when they got the feedback from Nacht they made another map with more features. I think in the Verrückt interview trailer it mentions it in more detail.