Am I the only person who has never heard of ANY of this? I've spent the last 30 minutes reading various things and I still have no idea what has happened. What it sounds like is trollers are reaching such a point of boldness that the trollees are taking preventative action. I've seen a slow but steady shift toward more lewdness in game chat over the last five years and I see it as more of a general moral decay of our society that has abandoned a higher reference of morality. These are the folks who will be leading the country soon, and that's a scary thought.
My understanding (and this is only my personal account which may not be representative or totally accurate) is that there was an initial spat between a woman and her ex-boyfriend. He claimed she cheated on him repeatedly, including with a writer for Kotaku in exchange for better coverage. This inspired an initial surge of anger against the woman and she began receiving personal threats (it seems that the ex-boyfriend has condemned the personal attack on her). Other developers came to her aid and condemned such action taken against her. During this time, things began to blow up with people beginning to assert just how badly women in video games were treated. Many gamers responded to this assertion as overblown and not representative. They were shouted down as being misogynists or guilty by denial (see kafkatrapping earlier in this thread). Unfortunately, claims of misogyny were not only aimed at those that were, but those that weren't. This caused further backlash by gamers which caused further backlash by feminists until feminists began to proclaim that the title of "gamer" was dead. This caused something of an uproar that immediately seemed to die down and be replaced largely by attempts at reasonable discussion by most gamers. Misogynist and some non-misogynist gamers did not quiet and continued to be angry, leading to further assault from feminists that continued to include even those that had tried to open up avenues of reasoned discussion. Now, that would be bad enough if you had two political camps fighting (because that's really what's happening here), but things get more complicated when you consider the gaming media.
The gaming media is left-leaning and is largely distrusted by gamers due to inaccurate reviews and previous wrongs. Recall that the initial woman was allegedly in a relationship with a Kotaku writer in exchange for better coverage of her work. Well, when you've got a bunch of people that dislike something, it doesn't take a lot to turn those embers into a flame and this seems to have done it. Swarms of accusations of corruption followed as people began digging (I do not know which accusations are accurate; I'm sure most are harmless oversights by those involved that anyone could have done, but I'm also sure there are some that are legitimate and major concerns; I do not claim to be knowledgeable enough on the subject to differentiate which is which). The media responded to these accusations with three things: silence, censorship, and accusations that those making the allegations were misogynists. As one can imagine, none of the above is a great way to garner goodwill of gamers, so #notyourshield began by gamers who are not straight white males (often with audio, photo, or video evidence as such due to initial allegations that they were lying), attempting to assert that trying to hide behind moral high ground and calling anyone who disagrees with you a misogynist is poor practice and does nothing to address the legitimate concerns of corruption in the gaming media.
I've probably got some stuff wrong/out of order/over-simplified/other, but I think it gives the jist...