The thing you describe does not verify that something is human made or ai made.
The only thing this does, is verify membership of a linked network of posters. Like a friend of friend in social media. And you verify if that friend's friend is also member of a separate exclusive meta social network on top of having an account on that social media platform you are trying to read the post on. Effectively whitelisting members.
And that exclusive meta social network has the membership entry bar of: please promise to not post ai content.
This will not catch retweets of questionable posts or any other kind of social media sharing.
Frankly, this is never ever going to work, not for the intended purposes. Just to put out a ball park number for the scale you need to consider:
Facebook removes over 10 000 000 fake accounts per day. So if you want this to fly on social media you have to prepare for that. And you have put examples on your site, how this is supposed to work on social media by just not showing the fake ai posts. Bad actors would find ways to exploit this network and it gets worse. The added trust of your friend's friend trust zone, would make you believe the fake posts even more, in the time frame it takes to remove the bad actor. And if you regularly have to remove bad actors, the whole concept of trusting the posts of members of the network is made obsolete.
For game publishers, if you use the concept of trust, there is just that. You do not need an added layer of tech for that. Especially not a place like Steam. If they ask you to disclose your ai usage and they catch you deliberatly lying and doing false advertisement, they will give you trouble. And big game studios will just not buy assets from an unknown asset creator that published a hundred of those on Itch. For that matter, not even small studios will do that. It is hobby developers that do.
And in my opinion, no one cares if a hobby dev uses ai.
The current trust system on Itch is, that you need to disclose the assets you publish. So if you look in the info box on an asset page, it will say ai generated or it will say no ai used.
Now, what about people lying? Same problem as in your proposed solution. You need to remove those. If you find proof that someone is lying, report it to Itch and let them deal with the fraudster.
I just do not see the problem (for games context). This is not something where people get rich quickly or can scam millions, or try to influence politics. There is too little incentive to lie.
Do not get me wrong, a method of blocking bots and fake posts on social media would be wonderful. But your method is just shifting the sign-up process from a platform to yet another platform. It is not dealing with the problem of bad actors or solving the problem of securing the sign-up process for social meda and it does not deal with people posting ai slop or fake news.
And using such a method for ai games, is just overengineering. If you need trust in the actors, just trust them to not tell lies about the ai status of their creations.
On your site you used a game published by Paradox Interactive. This is how a Steam ai disclosure reads for one of the games they published:
AI Generated Content Disclosure
The developers describe how their game uses AI Generated Content like this:
We leveraged AI-generated content to enrich our game with elements that would have been otherwise challenging to include. Specifically, we used AI for the AI character voiceover in different languages, a feature made possible thanks to this technology. In this case it made even more sense since the character is actually an AI. Otherwise, all the core art and visual elements of the game have been designed by human talents.
(Steam does not care about ai assisted programming. Only about things that influence the content directly. Not methods how to code the same function faster.)