I don't think video games have been shown to cause any violence in youth. We could say it de-sensitizes kids to violence, but so do movies and the news. I teach middle school and pretty much all of the kids are de-sensitized to violence, though only a fraction of them play video games. More are de-sensitized by TV shows, movies, or news. There is no avoiding this de-sensitization today.

But there's also no proof that such de-sensitization leads to committing acts of violence or is irreversible. I teach 8th graders, and you can get them to understand real violence and real tragedy (and adults in their lives should - for instance, we do a Holocaust literary unit and we also read texts about slavery, war, refugees, etc) and be sensitive to it in certain contexts. It's not like they're ruined forever. It's just that society is currently in a state of de-sensitization to violence; this is a societal attitude that shapes what games and other media are more than something that media has taught us.

That said, I don't have a black/white stance on 'video game violence' in terms of whether I think it's all good or all bad. I think Hatred probably deserves an AO, based on the text of the actual rating and what I've seen of the game. I think the context and type of violence in it looks off-putting and like something no responsible parent would allow kids or teens to play. I think it looks like something an adult should be allowed to play and that should be allowed to be made, but I don't think it looks like something that should be free of criticism. It's clearly meant to be gross and for shock value. And yet I don't feel this way about all video game violence, so my view on video game violence isn't black/white.

But I don't think we have any proof video games, even vile ones, have any real tie with creating actual violence. Most studies, data, and statistics suggest the exact opposite.