Now is the perfect time to release a game purely about rioting, preferably based in London. I would enjoy playing it. I want to destroy peoples property, mug the vulnerable and fatally wound the police and burn shops. Would be so much fun (possibly, I know GTA4 is fun)
Because I would never do anything like that in real life, or want to. But in a game you can release the mind and "play" as a violent thug that doesn't just have no conscience but revels in the pleasure of causing harm. And as soon as the PS3 is off, it's as if it never happened. And it didn't in a reality sense.
The healthiness of violent video game playing is well documented in science.
It's healthy for healthy people, perhaps not for those with violence issues.
The only negative is being called sick for recreating and playing something from real life to enjoy it's badness. I think this moral feeling is a shame. As the worse and most sick the game the better it is for you in terms of moral release.
Movies are different, I think they can be harmful, as you are being fed the harm rather than doing it yourself within your own boundaries. It would be ok to enjoy being a serial rapist in a game, but not to enjoy watching it in a film. It's interesting as I haven't thought of it like that before.
In a game you are very aware of playing and creating your content, as an isolated observer of film you are out of control and vulnerable.
Back to rioting specifically, a game of it could achieve balance by giving the option to play as rioter/police/ or innocent bystander caught in the wrong place and the wrong time.
But it's inevitable the most enjoyment would come from doing the nasty stuff.
That would include being the riot police role, and running round a corner to knock a boy off his bike and circle him to beat him to a pulp and then move on. Robust Policing 3, out next Autumn...