As we already knew, ZombiU originally started out as Killer Freaks From Outer Space. The thing is, that's not the only concept the game existed in.
You're looking at artwork for Attack of the Killer Rabbids from Outer Space, whichwas a 360/PS3 project back in 2012. This is what morphed into Killer Freaks, which then turned to ZombiU.
You can check out art from both iterations of the game here.