I think you forgot to read the description where the download is. It's under the "Completely broken" section. And it also says "Keep in mind that the Wii U port is in early alpha. It will likely crash, freeze, perform poorly, etc.". This software is also made in people's spare time. They very likely got a job. The Wii U is just not top priority. Most people play on their computer or phone. If you are good with C then you could contribute.