Radio, movies, television, modern art, journalism were all corrupted (by Frankfurt School philosophies). Video games are now a bigger industry than any of those, so of course the cultural subversives have been attempting to conquer it.
It began with post-modern-like "art games" which became a major part of the indie game scene, which was signal boosted by their journalist friends, which was happening as early as 2008 (or even earlier). Slowly, games journalism had been becoming more corrupt, cooperating with big game companies in reviews of their games, and continuing to a boost an increasingly political indie game community. Most of the biggest indie game successes, such as Super Meat Boy and Minecraft, had nothing to do with this community, and the early successes, such as Cave Story, were made before there was a community at all, but their successes legitimized others that called themselves "indie," and with the help of cooperating journalists, a cultural subversive tumor grew.
It was only in 2014 at the start of GamerGate did the opposition to this go beyond 4chan and blogs, at around the time when people began to acknowledge the internet "SJW" insanity that was picking up, especially on Tumblr. Thanks to this movement, their influence has waned and they have become a joke.
Marxist undercurrents have yet to be truly entrenched in gaming; that's only the case for its dying journalism. But only if gamers continue protect it.
My only concern with GamerGate is that the bulk of it was driven by a desire to be completely apolitical, to the point of being nihilistic. This seems to contradict their attachment to a gamer identity -- without values, what meaning does this identity have? Slowly, through 2015 and 2016 they did develop some values, such as for free speech and creative expression and individualism, but they have a ways to go in order to solidify an identity and value system that's stable enough to not be subverted like the rest.