Techland has explained that Dead Island: Riptide, which is due to release on the PS3, Xbox 360 and PC, won't be coming to the Wii U because they preferred to spend more time refining the current generation versions.
When speaking to Digital Spy, Alexander Toplanksy, the creative producer on Dead Island: Riptide said "One of the opportunities we had for Riptide was to continue the development of the engine, and really improve it and make a lot of refinements. The things that are required to bring something to a new platform, you need to either really get to be integrating it deep into the engine, or you've got to [do] a port."
Riptide is due to release on the 23rd of April in North America and the 26th of April in Europe, but because of these decisions, the only Zombie experience open to Wii U gamers will continue to be ZombiU.
Source: Digital Spy