Cemu
Cemu is a Nintendo Wii U emulator for Windows. it was the biggest breakthrough in emulation for the Wii U. While there had been a couple of attempts prior to the release of Cemu to emulate the Wii U, none had managed to boot up a Wii U game or get near being able to get in game.
Cemu had popped seemingly out of nowhere, with version 1.0.0.0 being released in October 2015. Before this emulation of the Wii U was seemingly out of reach but Cemu proved that it could be done when it could successfully boot titles to the loading screens.
Shortly after the first release, games started being able to get in game with varying degrees of speed and graphical issues. As of the latest version, many games are in fact now playable. Games such as Super Mario World and Mario Kart 8 can now be played through from start to finish with little to no issue and startlingly accurate graphics, though there will be issues here and there.
Cemu has come an extremely long way in an incredibly short time, in little over a year it has gone from just being able to boot games to being able to successfully emulate a few games completely at high speeds. It is definitely an emulator to keep an eye on as so far it has been extremely promising.