It's certainly "fancy", but... as someone who has been forced to go down this road more than a few times for desktop and mobile platforms please do NOT encourage this. The level of manipulation and monitoring of key events necessary to get even close to parity of normal input behavior and accessibility, which this example unfortunately doesn't do very well, is enough to drive one into voluntary retirement.

It's fun to look at and play with, and I know it has some useful applications, but it quickly becomes incredibly fragile and is guaranteed to waste time and effort that can, and should, be spent on other stuff. Unless of course there is nothing left to do and you're just looking for ways to torture some poor soul hopped up on Red Bull or Mountain Dew.

That said, I definitely do encourage anyone interested to explore how this stuff works. My experience has been that design pretty much overlooks input behavior in general, but there are some pretty impressive things that can be done now without painting yourself into a corner and exploring stuff like this is probably one of the fastest ways to figure out where the boundaries are.