matterbandit: Not sure what you mean by "start with the game icon from the offline installer"? I'll try restarting my computer and "repairing" my install using Galaxy to see if that works.
I don't use GOG Galaxy to launch or install the game (I use it only if I want to quickly update the game via file checking), instead I rely on the offline installers (your game library > click on the game to expand the icon > Offline installers). I do this because I want to keep exact control of the versions I'm playing, and for network features I need anyway to just launch GG without using it, otherwise I won't have network features and my Avatar name in the game would be 'Explorer' instead of my real account name. Without network features, you won't get the initial choice page MP - SP when launching, it's the same as if you would play offline without connectivity whatsoever.
So, essentially, you must or use GG, or start the game from the Offline installers + launching GG if you want all network features. I chose the 2nd one for better version control.
