What you'll want to do, is go to
Build Game in the
File drop down menu in
FPSC. Once there, navigate to the second tab along the top called
Level Settings, then click on the
Edit button for
Global Script. A window will now pop up with a plethora of different settings you can play around with to get a desired look in-game. For example, this is where you'd go to change the skybox. However for what you're looking for, you'll want to go down to the
Ambience Level fields, and change the number to something like
0 or
1; zero means that there is no light, it is pitch black. Make sure
Ambience Level, as well as
Ambience Red,
Green and
Blue all have the low number, thus making the in-game ambience dark. Now what it looks like is going on in that screenshot as well, is a little bit of fog action. I'm not sure what color variety they've got going there, number wise, but you can now go up to the
Fog fields, and start playing around with different numbers for effect. Make sure
Fog Active is simply set to
1, then manipulate the color scheme of your fog with the different colored parameters.
And that's about all I can say! Make sure when you're done playing around with settings, you press
Ok, and then
Ok again on the original window for it to take effect. Also, I've noticed that if you change a parameter, say
Fog Blue, or any for that matter, if you don't click on something else that hasn't been changed, before clicking
Ok, the change will not take effect on that parameter. When you've changd something, just click on another field you haven't played around with, then save the settings.
Cheers
Life would be much easier if I had the source code.