I could care less for gratuitous gore and six.
Um, mature content does not necessarily mean excess gore and/or six. It's just something people think of when they think of some Mature games.
I think it can also include mature situations or controversial or disturbing/creepy topics or strong language, etc.
For example, a somewhat hardcoe controversial JRPG I loved playing a long time ago was http://en.wikipedia.org/wiki/Shin_Megami_Tensei_III:_Nocturne
It was the first Mature game that I bought for myself.
However, it didn't really have excessive gore and/or six shown from what I have played. It was just plain strategic turn-based combat but with limited amount of turns and LOTS of encounters, lol. There is no blood when striking others. I only see "sparks" of light when you smack someone.
No, I think it was the disturbing content of demons, cults, (a hospital used as a place for cults), murders, religious content and references, conspiracy....and the apocalypse, not to mention the controversial part where you become part-demon and fight a god that sort of represents the "god" with a capital G who acts like a jerk and tough angels who believes power/strength is everything, lol! You can even get the Four Horseman of the Apocalypse to fight on your side, lol! Some of your buddies turn into demons and become kind of psycho (or dictator-like). There was even a guy that makes clothing out of people's faces. (Talk about disturbing!).
There were only a few female characters that were partially nvde (but not even that nvde--think skimpy bikini-level, and one female had a snake wrapped around her nvde body which covers the parts anyway) and a hallway of blood. There is no six, just flirty/implied comments. There is an optional boss called a http://www.youtube.com/watch?v=AvmkVddRxfI, but that's really nothing too bad. There was no gore really to speak of (besides the occasional dead body, maybe, but nothing detailed.)
Sorry for rambling. I just wanted to give an example of a M-rated game that does not have excess gore or six that some people think that all M-rated games have. =)