The origins of #gamergate explained in three paragraphs.

First, we have Anita Sarkeesian, she makes controversial videos about women being sexualized in video games, not everyone agrees with her but she mostly declines any kind of debate closing comments on her videos. Then, we have Zoe Quinn, a female game developer that made a game around the theme of depression. She publicized herself on "Wizardchan", a forum of depressed males, most of them recognize and take pride on being virgin at an older age.

In the twisting point of this controversy, the Ex-Boyfriend of Zoe Quinn, released a post on tumblr accusing Zoe of sleeping with 5 journalist of several websites, some of then working for sites like Gawker and Polygon, all of this with the purpose of getting good reviews on her game. People at Wizardchan didn't received this news lightly and became enraged at Zoe, some of them releasing private information of her in "revenge". Meanwhile, some gaming blogs and news sites like Kotaku reported that Anita Sarkeesian had received death threats that forced her to flee out of her home into a friend's house.

The last twist of the story, was a series of articles in several gaming blogs and news sites, pinning all the aggression received by Zoe Quinn an Anita Sarkeesian on the entire gaming community, proclaiming gamers dead and stereotyping gamers as a community full of "white angry manchildren" full of misogynistic tendencies. The gaming community didn't take this lightly, demanding more respect from people working at these sites, finding only mockery, censoring and banning left and right.

THIS is what started #gamergate, and this is what #gamergate is: a call for the right to not be demonized by sensationalist gaming journalism.