The answer is no. Done. Next topic.

So much this. People so many times act like they're oh so mature while all they doing is sitting in front of a TV pushing coloured buttons. Gaming isn't mature, playing games isn't mature. Mature is taking responsibility, working your arse off, take care of your family, do something good for society, get active in politics or something. But you know what? Being mature isn't fun. So I'm happy to say that there is still a child inside me and every now and then I decide to let it out and I'm absolutely fine with that. 

A MATURE game to me is PAPERS PLEASE. Such an adult narrative and concept. I love that game, they should port it to consoles.

Oh yes. a mature hobby is camping, bushcrafting, fishing... In those activies we see the children separated from the adults. Men or women, gotta have fiber to face nature.

Some of them are, to an extent, but most of them aren't.

It depends. Ratings are made based on the content, though realistically the content isn't always the most appealing to its own audience. I've played M rated games that handle mature themes in an interesting way, and I've played M rated games that go super Edge mode with blood and sex all the over the place. The former I find appealing, the latter I find is targeting a demographic I haven't considered myself a part of in over a decade.

Of course, I wouldn't say mature themes always involve better writing; I've honestly played E and T rated games with more interesting plot lines than many mainstream M rated titles. Someone above mentioned "convoluted storylines" as something more likely to be present in M rated games...which kinda confirms the point in a way. I can honestly say such a thing holds much less value to me than a more naturally flowing narrative. This is something that I feel applies to movies, TV shows, and manga I follow as well (I've written posts here on the shonen vs. seinen distinction)....but I guess I don't need this post to rabbit trail any more than it has.

Anyways, I play the games that interest me, regardless of the the letter on the front of the box. If someone were tell me the rating of a game is directly linked to my maturity level, I can only offer them pity in return.

"Mature" is not only a warning toward parents with younger children but also a commercial tric for selling more games...

Does it have something that is actually challenging and thought provoking in a positive way in it?
If the answer to that is 'no' then the game probably isn't actually 'mature'.
But who cares as long as it's fun? ;)