I think the reason M games seem to appeal to kids more is because of how many of the high budget, great games coming out these days are rated M, not just because its ZOMG VIOLENCE.
Maybe I'm wrong, but none of the people I have ever known get these games simply because they spatter blood and guts around, but because they are fun. If anything thats only ever been a turn-off for most of the gamers I know, though its negligible to them at best.

GOTY Contestants this year: Dead Space 2, Dark Souls, Tales of Graces f. Everything else can suck it.







