The Legend of Zelda: Breath of the Wild had been out less than two days before the developers of Cemu (an in development Wii U emulator) had the game running on their PCs.
One of the emulator's creators, Exzap, posted a video of the new Zelda game which, they claim, is capture from one of their PCs:
The build clearly has problems. Link is sinking into the floor at points, none of the runes work, and the framerate appears to have severe stuttering - more so than I've experienced playing the game on the Wii U over the weekend.
Exzap shared other details of the build on Reddit, revealing the video was recorded on a really powerful PC - an "i7-4790K, GTX 780, 8GB RAM." They chose to "not alter the speed of the video to best represent how it actually runs. But I did prepare a shader cache so there is no extra suttering [sic]. Audio is muted because it is just white noise."
Exzap only included a brief list of bugs but a lot of them are major. "Lots of bugs that make the game unplayable," they wrote. "Physic glitches, rune abilities that require object selection don't work, no water collision, etc. Essentially it's impossible to leave the tutorial area without using a save."
For the moment, too, the problems seem insurmountable, "What you see in the video is pretty much what you will get. The remaining issues take longer to fix and performance will also not change," Exzap said. Adding in a later comment the game's speed is "CPU bound. A better GPU won't really make a difference."
The Legend of Zelda: Breath of the Wild is the last big game from Nintendo that will be coming to the Wii U; all of its attention will now be focused on the Switch. The Cemu developers have had a lot of experience in hacking games for the Wii U so it's not so surprising they have managed to get Zelda running on the emulator. Still, doing it in a matter of days, not weeks, is what stands out.
With the Switch rumoured to be running a version of Android, Nintendo may be looking at the speed at which hackers cracked Zelda, and start feeling worried that it won't take long to make a Switch emulator.