10-16?

I have chosen an audience of 10-16 years old because content I could use. To be sure I stayed in the age group boundaries I was looking at games, and their "pegi" labels.

PEGI 7 Any game that would normally be rated at 3 but contains some possibly frightening scenes or sounds may be considered suitable in this category.

PEGI 12 Videogames that show violence of a slightly more graphic nature towards fantasy character and/or non graphic violence towards human-looking characters or recognisable animals, as well as videogames that show nudity of a slightly more graphic nature would fall in this age category. Any bad language in this category must be mild and fall short of sexual expletives.
Pegi 7+ type of games: http://www.ea.com/uk/simulation/pegi-7
Pegi 12+ type of games: http://www.ea.com/uk/rpg/pegi-12
In the games for older teenagers there is more action, more shotting and fights. It looks like those type of games are more popular, but of course games like sims also have big fanbase (usually conflict/war/etc. games vs peaceful games).
I chosen to go with the conflict/war vision, because of the way cancer act towards body.