I agree with the lighting problem, the overall scene is far to dark.
However i understand the feeling you are trying to generate here, so perhaps just increasing the range of a light source would allow the player to have a good idea of whats around them without turning up the contrast on their monitors while still creating the dark atmosphere your aiming at

well first off, excelent work.
i petty much agree with most of the stuff said before this.

the problem that i see is that your dev team might need to re-evaluate their target audience.
If its more mature like your saying, then mess some things up, and add lighing with evil tones of color in it (red/blue/ect). Also mabey change the curser.
If its more child like, then try to use more earthy or pastel colors in your work.
If its an all-around audience, then realism would probably be a good goal. I believe that people have comented on that part already.

let there be light

Zero

Excellent work. I look forward to playing your game when it's finished.

One of the suggestions that I have, is about the health and mana bars. Problem with them: Too fake, they standout waaaaaay too much. My solution to that problem would be to alpha blend them to the sides, or add a few "container" graphics that are pretty and have an animated texture for either(a la Bloodlines' GUI).

As far as your worlds, the problem with the graveyard, is that it's too stark. The differences in the tiles is just nasty looking. Create a larger area that creeps around, patches of dirt overlapping stone tiles. Don't make it measured and defined, give a morphic feel. This adds the feeling of character without requiring too much work on the part of the artist(points at EDI).

Engine-wise, everything seems to be working out for you. Technically, there's nothing there that seems to need work. The fog and water you have down. Camera sounds good. Lighting seems alright. One idea for lights(don't know if you've already done, but I would bet you've at least thought of it) is allow flickering lights. Maybe have them move, such as a flame wafts in the wind and have the light move with the animation.

So, in sum, add a bit of irregularity to your worlds. Build them perfectly, then, say, destroy them. Think of what would happen over x amount of time. How the dirt would move around in the graveyard, how plants would waft in the breeze or wither, how stone would crack, etc. Bring life to your worlds. You don't necessarily need to create a huge number of new tiles, but spread your worlds out with a bit of spontinaity.