Lighting and Sky Box

So for lighting and sky box im pretty much finished making all those decisions, i want a dark feel to the game seen as its their last stand at the beggining of the game.
Below are some examples of what im thinking lighting wise for the feel of the game and some forest photos for what i would like the banks to look like:

Sky box is going to be mostly dark clouds and grey skys kinda a mixture of the following:

mostly the fist picture though will be what im going with for the sky box