The initial scandal was that Nathan Grayson had been friends with the relatively unknown developer of Depression Quest for a long time, to the point of getting thanked in the credits of the game. He then plugged it, here:

http://www.rockpapershotgun.com/2014/01/08/admission-quest-v...

And also covered her here:

http://tmi.kotaku.com/the-indie-game-reality-tv-show-that-we...

...without disclosing the relationship. Which could have been resolved with a simple apology and adding disclosure to the articles, but several major game sites instead responded with such a storm of ridiculous charges that game journalism was instantly sullied even more than it already was.

Because of this, GamerGate has been poorly covered in most game sites and rags like TechCrunch, so it's not surprising that you hadn't heard of this.