Not so many rules now that my youngest is going on 17, but before I was pretty tough on what games the kids were allowed to play in the house.

I didn't go by ratings so much as context. A very violent fantasy game (chopping orcs and such to pieces) was often acceptable. A game with real world violence and crappy morality, like Grand Theft Auto, was right out. Much depended on the motivations of the characters. A little evil was okay if it was Marvel-comics-style evil.

In my opinion, your character slapping a woman on a New York street is a lot worse than your character ripping the guts and spine out of a zombie. May not sound sensible to anyone else, but it clicks for me.

Some were tricky. The "Hulk" games allow you to be the Hulk, and rip the crap out of Main Street and innocent bystanders. That one passed muster, but primarily because the kids were older when they played it.

The best games are morality tales of the old kind. Some allow players to make moral choices and take the consequences of each direction. Sometimes this works out, sometimes it doesn't. Sometimes I don't know. My son once turned a character to evil just because it would allow the character to fart.