14 DAY TRIAL // If you're asking why one would play Halo (PC version) with a guitar, forget about getting a good answer 'cause this was done just because it could be done. Scroll down to the bottom of the page to see the video. First of all, let's all agree that this is no fake, as you can clearly see that every on-screen event is determined by fret pressing and handling of other controls found on the X-plorer guitar controller for Guitar Hero II 360. It wasn't long before anyone tried anything like this. I know I used to try all sorts of combinations between controllers, GameBoy and NES, and once I even managed to connect a NES controller to my PlayStation, but I didn't successfully play any games with it (only one command worked).
Surely for playing Halo with the X-plorer guitar on your PC, there would have to be some major soldering involved, which I personally don't recommend if you have an expensive one. Connecting the guitar's frets to where the keyboard buttons hit the bottom should have been pretty easy. What I can't possibly imagine is how the guy connected the strum bar to the keyboard. I mean, yeah connecting it was easy enough I'm sure, but what exactly did he connect it to in order to get the same effect. Keyboards have buttons that go up and down, not analog sticks and handles. As you can see in the video, frets are used.
Again, don't criticize! This so-called invention doesn't necessarily have a purpose (heck, I'm sure Halo sucks played with a guitar), but the idea was that it could be done. Nothing more, nothing less. Although I don't see anyone trying to play console games with keyboards... Oh yes, that's why they bought consoles in the first place.