I feel like there's a lot of missing information here regarding the "controversy."
I normally only lurk but I've made an account to describe the recent events as objectively as I can, in as few words as I can. Bear with me. The tl;dr is that gamers aren't angry at any one thing. This controversy was built up from various incidents that eventually led to gamergate supporters trying to defend the gamer status from one-sided media bashing.
Act 1: Wizardchan
Wizardchan is a "chan" site for male virgin nerds who suffer from depression, social anxiety, etc. Nobody here really cares about Zoe Quinn. At best, 2 users posted about her. ZQ supporters alleges that Wizardchan orchestrated a raid on ZQ, doxxed her private information, and harassed her on the phone. Wizardchan denies these allegations. Some question how "a bunch of virgin nerds deathly afraid of talking to women can harass ZQ over the phone?" Supposedly, various users claim that any private information of ZQ were all fake. Redditors say ZQ faked her harassment in order to play the "victim card" in order to gain mass support for her upcoming game Depression Quest.
Whether that is true or not, it's undeniable truth that she gained a mass of support for the game on steam greenlight, a majority of which were from users who had no intention of playing the game, but are supporting the game only on the basis of her alleged harassment. (Source: Various comments on the game's steam page).
Disclaimer: It is true she surely did receive some harassment, but I think it's also very likely she embellished those harassment, even making some up in order to use it for her personal gains, which is what many gamers in the movement believe and were angry about.
Gamers and Redditors were angry about this, but not very much actually...until...
Act 2: 5 guys & Mass censorship
In August, ZQ's ex released a very lengthy post (with chat logs) about her cheating, manipulation, deceit, etc. His claim for the purpose of the post was to reveal her true personality to the people who might get close to her, in order for them to not get hurt by her manipulation.
This did NOT spark any outrage. People were angry and questioning journalistic integrity, but it was only a relatively small group of people. I would say the biggest reason as to why the anti-ZQ, anti-corruption group of reddiors exploded in population is because of curiosity. Posts about ZQ were censored or had comments deleted en-masse. This prompted the users to reposting those discussions many times over which received the same treatment. This mass censorship made many curious redditors, including myself, research and dig information regarding the recent events. More people became aware of this due to the censorship.
There is evidence that a mod of one of the gaming subreddits made contact with ZQ on twitter. (source, tweets between elchupacupcake). She allegedly asked the mod and various other mods to censor all topics regarding her. They did.
Basically, at this point people were over the fact that ZQ slept with 5 games who were prominent in the indie gaming industry. People were mad at the censorship and mass silencing of opinions.
At this point, I probably lost all of you so I'll just list the titles of what I planned on writing
Act 3: Smear campaign against gamers. Gamers of reddit denounce corruption and journalistic integrity. ZQ supporters & Media ignore the issues of journalistic integrity and censorship, and focused on painting all gamers as misogynists. Within the span of a few days, dozens of similar articles popped up, allegedly under the influence of Silverstring media (who has close ties to anita sarkeesian and ZQ).
Act 4: Gamers retaliate to the smear campaign and the attempt to silence gamers via gamergate. One big, side issue that arrived here is if you follow gamergate for a while, you will see that both sides are receiving harassment and death threats, not just SJW. Some people are angry at what they consider hypocrisy on the side of the SJW who ignore the death threats their supporters make to others, but will easily paint all gamers as white male misogynists when at any given chance. There are some trolls antogonizing both sides here, but they go unrecognized and are seen as representatives for the other side, which is not helping at all.
There's actually a lot more going on than I have time to write about, but this is a large portion of what led to gamergate. Once gamer gate started, there has been a lot of other things becoming clear, such as trolls who purposefully add fuel to the issue by harassing the SJW side, or the SJW harassing people who don't agree with the ZQ and Anita supporters.