I think it's important to state that there are differences between "dark" and "mature." Having a lot of violence, death, oppression, rape, etc. certainly makes a game more dark, but I think it's a very different thing from mature. You can have a mature game that isn't neccisarily as dark as the one you're talking about. Sadly, my view on what makes something mature (difficult moral decisions, shades of grey) has become very different from what most mainstream media sees as mature (lots of pointless nudity, objectification of women, needlessly gratuitous violence, and other things that I ironically see as being far more immature then "mature").