Guitar Hero, and in general rhythm games with instrument-like controllers, were certainly not the first games of this particular genre, as rhythm games have existed for quite some time, but the popularity of such games really exploded with Guitar Hero (with the first game alone selling over 1.5 million copies, not to talk about the various sequels and spinoffs).
This started in about 2006 with the first Guitar Hero game, and it was quite a craze. Then came another game, and then another, and spinoffs, and competing games using similar instrument controllers, and then... *poof*. Nothing.
The market got oversaturated and the craze died out almost as fast as it started, somewhere around 2010 or 2011. It just... disappeared. Almost nobody plays any of the games anymore. What once was a staple of parties is basically nowhere to be seen anymore. (Ok, some people probably still play it, but you don't see much of it anymore. It has pretty much disappeared.)
Talk about a temporary fad. This would be a textbook example.
What makes this quite particular is how short-lived it was. Of course there have always been very short-lived fads, but here we are talking about an entire genre, rather than eg. a single game series. I can't think of any other game genre (or, for that matter, any kind of entertainment genre) that has seen such a rapid raise in popularity and then an almost complete fallout in such a short period of time. And it's not like the genre faded into obscurity slowly over the decades or even years; it fell out of popularity quite rapidly.
I'm left to wonder why this happened. Why did people suddenly get sick of the genre? After all, people enjoyed it quite a lot when it was popular, and it was fun to play. What killed it so completely? One would think that given how fun it is to play, it would still be played, but no. Apart from some small minority, almost nobody is interested anymore.