chang3r: You can install games completely offline on GOG?
I did not know this. Great feauture.
Can't remember when the last Steam Patch was dropped (i think Version 2.07.3 about 11/21 or something like this), but since the patch you get an key error on Steam. Since i like the game, i would consider buying it here, maybe next sale or so.
If you go to your library page via the website you can then download the offline installers and then install straight from them. However, as I've never used Galaxy I'm not sure how, if it's installed on your machine, it will interact with the game when installed but I know that I can play both games without any internet interference.
As for the versions that are currently on GOG, Two Worlds Epic Edition is 1.7a and Two Worlds 2 Velvet Edition is 2.0.6 which implies that the Steam update has not yet made its way here but if/when it does the game should still be playable without an internet connection thanks to GOG's DRM free policy.