First off: This was in Latvia. I have no idea how Latvia rates games, or if they do at all. That could be a moot point.
That said, I feel like I'm one of the only ones who doesn't see it as a laughing matter. A kid died - that's not funny.
I think this is another case of "blame games for issues" here, and one more that shouldn't exist. The kids were too young to be unsupervised, yet too old to not know what would happen. I'm thinking that the parents are more to blame here. Even though I don't know much about Latvian culture, they should have taught their children that attacking people like this - even for "fun" - isn't acceptable.