What qualifies as a "mature" game?

[F0X]

NintendoPie said:
Good idea.
Mature is what the group that is allowed to play these games described as, I think that is a fair description of what mind set you should have while playing these types of games. Sadly, the 'M' on the box doesn't matter. Children, below the age of 12, have got Dead Space or God of War. It is quite pathetic and should not be allowed. A person who is over the age of 17 should be allowed to chose to buy the game if it's what they want. 11 - 16 should need Parental Consent and 10 and younger should not be allowed to get the game at all.
That's how I feel about the 'M' regulation. I hope I'm OT.

You're on topic. In terms of ratings, could a T-rated game be considered mature if it deals with mature themes? Could Uncharted, Metroid, or Infamous be considered mature in any way? Or is it completely and utterly dependant on audience?

Also, I know that there are immature people over the age of seventeen who play M-rated games (certain relatives come to mind). Should they not? Or is maturity so defined by age that it doesn't matter?