Back in the day (90's-early 2000's) it was hard to see how the right would ever really appeal to the younger generation (people were less politically engaged in general). There was no "alt-"right, just the traditionalists and Christian fundamentalists screaming about how Dungeons and Dragons is Satanic and shit like that. Those guys were incredibly lame, and very out of line with the sentiment of young people at that time, which was generally a kind of "free speech absolutism," brought on by being the first generation with access to the internet. Shock images/videos were common and being able to handle that sort of thing was a point of pride. Pretenses of respect and decorum were stripped away in favor of the raw and unfiltered.

Gamergate was the moment when this energy really began directing itself against left/liberal/minority figures, and took on a more explicitly political character. Because sometimes those people would critique video games and commit the cardinal sin of caring about things, while also sometimes disparaging things that people liked. Certain women became targets of hate in certain communities, and it wasn't long before rumors started circulating that a female game developer (who was frequent target of hate) got favorable reviews because she was sleeping with the reviewers. Thus the famous line, "It's not about misogyny, it's about ethics in games journalism."

As liberals and leftists were not really on board with all the harassment campaigns and violent threats, and they faced more and more criticism from that direction, and they eventually formed into (or at least formed a key component of) this "alt-right" movement that rejected the pearl-clutching and feigned piety of the traditionalist right, while still hating minorities and progressives and all that.

If you don't know about gamergate, I almost don't want to spoil that.

This is one of the better summaries of gamergate and how it shaped the "alt right" movement, imo.

https://www.youtube.com/watch?v=lLYWHpgIoIw