Firstly sorry for my eventual english mistakes.
Now for the forum color:
I have to say white on black is really aggressive and makes eyes tired.
You should try a clear grey, it'll be better.
Because for now the contrast is too hard.
But then it's 3:30 AM for me so maybe my eyes are tired of computing.
But I think not.
I also want to add I just finish the cold plain and now try the hard next level.
But seriously, it's really full of good idea (portals justifying the appearance of fallens, some new skills, the zombie dying and then his skeleton only respawning,...).
Seriously, I love it.