STEAM updated directly to 0.5.1.5 alpha
I switch to fullscreen in graphic options,
now Steam opens and directly close the Game,
no window appears.
No new start possible
Had to be an old error, I will find, what is be written to do now.
iMAC 27 (2011)
2,7 GHz Intel Core i5
12 GB 1333 MHz DDR3
AMD Radeon HD 6770M 512 MB
edit: fixed with
config.properties file will be found on MACs by pushing go to - menue in Finder and go to hidden Library folder