Most of our entertainment rating systems have it backwards, really. I think we need to rethink the categories in a way that makes more sense.
Everyone - May include moments of genuine optimism and hope.
Teens - May include references to sex, drugs, and violence. Let's be real here, this is the whole reason why you bought this to begin with.
Mature - Warning: Viewer may be subjected to scenes of adults taking responsibility for their actions.
Of course my favorite is "Game Experience May Change During Online Play". That one can stay.