Could not load main config file: config/ default__main_settings.cfg

[evlbluone]

have you moved any files around? Also try running the application itself not the shortcut to it.

This is the exact same issue on Mavericks for me. I purchased the game through Steam and did a fresh install of Mavericks.

I just upgraded to Mavericks as well. I was having the same issue. I download the patch updates from here and installed it:

http://support.frictionalgames.com/entry/100/

It now works. Hopefully this helps you as well!
If Mavericks won't let you open it because it is from an unknown publisher, follow these instructions to get around that problem:

http://www.wikihow.com/Install-Software-...s-on-a-Mac

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