Hi there!

The version of the offline installer for Windows is outdated. For Win users you provide the old version 1.2.19338 from 2016.
The latest Win Version is Version 1.2.35006. It's from 6. Sep. 2018.
(Link to post on steam:
[url=]https://steamcommunity.com/games/224480/announcements/detail/2680094378544216844[/url])
If a support person from GOG reads this and has the time: Please update it.

Kind regards