In addition to scheduling and budgetary concerns from wangyue's blog

According to Blundell, there was no planning, no funding, and no support for its fledgling horde mode, and the final product was relatively bare bones as a result, with only a single room and a rudimentary weapon upgrade system to WOTLK Gold keep players interested. Still, there was something undeniably magnetic about the studio's pet project--at least to its creators. "There was that kind of rock-and-roll aspect of it that we all identified with and gravitated to," admits Blundell. "It's got that kind of edge to it, and it speaks to us, and I think it speaks to the fans."

The one party Zombies didn't speak to? WOTLK Classic publisher Activision. "Even though Activision gives us wonderful latitude to explore different ideas, there are also certain guidelines that we have to keep within," explains Blundell. "When it comes to Zombies, and if you look at the birth of it, it was done in the lunchtimes of WOTLK Classic, which was already a very trying product in terms of schedule and so forth."

In addition to scheduling and budgetary concerns, Activision may have been reluctant to include something as ludicrous as Nazi zombies in its otherwise weighty game about a real historical war. "WOTLK Classic was a very serious game," observes Blundell. "It was talking about the Pacific campaign and WOTLK Classic, and the campaign finished with the atomic bomb. Not a light topic whatsoever." Given Activision's understandable concerns, the devs struck a deal: "Activision enjoyed it. We enjoyed it buy WOW WOTLK Classic Gold. People playing it all around the office enjoyed it. And so it got put in. The deal was: we wouldn't promote it, we wouldn't talk about it. It was purely an Easter egg."