First we found a 78-year-old Japanese gamer, now there's a 70-year-old Brit who is likewise an FPS enthusiast. He's completed Call of Duty: World at War single-player at all difficulty levels. Gamezine has the interview.
So, Brian's 70-year-old dad took on GTA IV and took quite a liking to it. Others his age are not as enlightened or - shocker - willing to try new things, and so the series might require further explication.