There's serious adult content, and there's silly adult content. There's funny violence, and there's silly comic violence. It can often be a fine line between the two, in both cases, and it's one Bethesda are well aware of during development of Fallout 3. Lead designer Emil Pagliarulo:
There are some people who say that making an 18-rated game, and especially making a Fallout one, should be about sleeping with the hooker, then waking up with the venereal disease. A lot of that stuff personally, to me, veers into being a 12-year old dungeon master.
Some of it feels right and some of it feels wrong. We're appealing to an adult audience and it's a tough call. I mean, once you have groin shots you're approaching a level of silliness that, if you're not careful, can pervade the whole game.
Hope it's not too serious. Those post-apocalyptic wastelands can be bleak. It's going to need something to lighten the mood.