Here's my old thread on it. Obviously it's been dormant for a while, but the links in the OP... while copious... do try and sum it up. I looked back at the Forbes article there by Erik Kain, and I'd already forgotten about the "Gamers are dead" backlash/coordination between games journalists... how they all worked together and wrote similar articles on how the "Gamer" terminology is toxic and over. Really was a bunch of stuff that all happened at the same time that sparked the outrage.
Anyway - Searching for a definition on Google is going to net top results from the offending places... Gawker, Vox, WaPo, Wikipedia, et al... with their explanations of it. Nothing unethical there... no sir.
Admittedly it grew to encompass far more than just unethical practices in the games industry... and became an anti-SJW sort of thing. Though the SJW stuff grew pretty rapidly alongside it, so it makes sense.
Here's a Medium article summarizing some of the early events: https://medium.com/@KingFrostFive/gamergate-august-2014-revisited-3b41832c061b
A few really shady things get people digging, lot of "streisand effect" goes on, big names get involved, and the movement is born. I really should go back and rewatch some of those Internet Aristocrat videos on it... I find even my current recollections hazy on the details of the beginning, and more focused on where we are now.
Edit: Heh, here's a "GamerGate in 60 seconds"
https://www.youtube.com/watch?v=5fnRSL3d_xU
Thanks GP. I had been of the opinion at the time that it was not of wider significance, but it has a surprising staying power bubbling beneath the surface (like Benghazi does for a segment of the population) so I wanted to get as unbiased as possible a deep dive on the subject. I solicited your recommendations because in current times one needs to be able to reject so very many search results out of hand and I was not familiar enough with the gamespace to know whose opinions to value