What qualifies as a "mature" game?

[NintendoPie]

F0X said:

But if the definition of a mature game depends on who should be allowed to play it (that is what you've said), would that rule out non M-rated games altogether? Because a game that doesn't have much, if any, mature content could be played by younger, less mature players... even if they are not the target audience. Or do you see my point of view- that a "mature" game is not so easily defined?

Maturity isn't easily defined. What I said, though, would easily take out non-mature people.