Nintendo says that you can't play a Wii U game from an SD card, but a workaround lets you do exactly that.
No, you can't play a game by using a SD card in the Wii U's card slot, but if you use a USB card reader in one of the system's USB ports and pop a SD card in there, you'll be able to play from it. It works just like a USB thumb drive in this configuration. According to a video we found on GoNintendo, read speeds aren't an issue.
It's not rocket science, but this workaround may not have been obvious to everyone out there.
Hyrule Warriors ships one million units worldwide, which is damn good for the Wii U
10:00 AM on 01.27.2015