FATAL ERROR - Could not load world file 'maps/main/owed'

[Urkle]

I'm referring to the "Game Launch Options" in steam itself.. As it sounds like somehow the launch options got set..

1. Right-click on the game title under the Library in Steam and select Properties.
2. Under the General tab click the Set launch options... button.

And as for the "~/Library/blah blah" that jens mentioned.. on OS X (and Linux) ~ refers to "my home directory".. So.. basically open up finder and press "apple-shift-G" a box will appear asking you to "goto". enter the path Jens mentioned. (Lion and higher apple hides the Library folder by default).