While pack-in Nintendo Land and New Super Mario Bros. U were the highest profile launch titles with the Wii U, it was certainly ZombiU that was next in line. An 18-rated, gory survival horror experience that made clever use of the GamePad, it was - despite the inevitable flaws that come with a launch day title - a strong showcase for the system. It's an exclusive that in future, perhaps, will be recognised more for its merits.
It's no secret that a prototype was once in development, as it was very publicly announced, yet it was ultimately cancelled and mothballed - the original had failed to make a profit. Naturally Unseen64 has been busy digging up details, and some snippets around the prototype that was in development have emerged. Primarily it would have featured a co-op mode, in which one player uses the GamePad and another uses a Pro Controller - though not a co-op mode, the original's local multiplayer option utilised both controllers in interesting ways.
The setting would have been post-apocalyptic, naturally, but more run down by the zombie hoards. In addition there would have been multiple routes in levels, possibly splitting up players in co-op. Like many sequels, it seems that the small prototype team was keen on taking it up a notch from the excellent but slightly rushed original.
Unfortunately it never saw the light of day, and isn't likely to be revived soon. Would you have liked a sequel to ZombiU, perhaps on the proviso it wouldn't be called ZombiU 2?