It's not the game play that bugs me...it's the story. When I was 10 I was playing Spear of Destiny and Wolenstein and Doom, plus a slew of fighting games. Plenty of violence and there was some gruesomeness in Doom to be sure, but there was virtually no story. You shoot the bad guys and that's it. You don't stop and pick up a hooker or bring yourself up to ethics and morals. The complexity is something that an adult can sort out and cope with, but sometimes it can just confuse a child.
Character development is the issue, in my opinion. I think that, in some cases, the extensive character development so popular these days encourages children to relate to the character...and that causes problems.
