Here's a good explanation from u/Throwawaycuzmeh:

Kotakuinaction's mission statement was opposition to censorship and bad journalism. It is impossible to oppose these things without opposing leftism itself. Virtually all bad journalism and censorship is coming from the left. So the sub began to organically tilt conservative.

The mods leaned more left, and they became obsessed with making sure the sub did not become "another T_D". So they implemented a ridiculously vague rule of "no unrelated politics". They then used this rule to remove content that was absolutely relevant but supported conservativism.

At one point, the mods actually put the rules to a vote. The users overwhelmingly opposed the absurd content removals. The mods didn't care. They ignored the results of the vote and continued arbitrarily removing content. Some of the mods became openly hostile to the users.

On a related note: the Kia mods lost their shit when users started talking trash about polyamory. I can't imagine the mods would have behaved this way unless one or more of them were engaged in the polyamorous lifestyle. We might have been dealing with literal cucks.

Credit to u/Ragnar_Danneskjold for putting it in the KiA2 announcement thread on thedonald.win

KotakuInAction with out the 2 is cucked. KotakuInAction2 is the based one.

The TDS-suffering mods at KotakuInAction wants to keep the movement focused on video games and not the greater culture war at large, mainly because we have discovered that the mods of KotakuInAction have became the censorious leftist monsters that we have been fighting so hard against and want to neuter the potent force (Gamergate) that may have ultimately gotten Donald Trump elected. The userbase revolted and went off to found KotakuInAction2 which are the true heirs to the vision, spirit, and mission of the modern Gamergate movement: to combat the leftist rot that have perverted many aspects of our lives.

I’m sure somebody else can give you more details but what I gathered from lurking during the split was basically that Kia mods were being overly strict and bending over for Reddit’s censorship agenda. While I may disagree with them personally I respect the way kia2 mods stand up for free speech.

I lurked on both for a while but eventually chose kia2.

People who posted on KIA2 have much bigger dicks than people who post on KIA.