Good Old Games allows to download single games over the website or over the client, but not the whole game library at once. Fortunately there is LGOGDownloader, an unofficial downloader for GOG on Linux.
sudo apt-get update && sudo apt-get install lgogdownloader
Create a new folder in the desired directory.
$ mkdir gog-library
$ cd gog-library
The following command will now download your entire library to the gog-library folder. You will be asked for credentials the first time. If enabled, two-factor authentication is also supported.
/gog-library$ lgogdownloader --repair --download --report --platform=all --language=en
Depending on your preferences, you might change or remove some of the options.
- –platform=all downloads the game for all available platforms. You can replace all with w for Windows, l for Linux, or m for macOS.
- –language=en downloads only installers in English.
- –report creates a log file lgogdownloader-report.log in the current folder.
- –repair checks existing downloads. It will download new versions of the game when available and add a suffix .old to the previous ones. It will also try incomplete downloads again. Keep this option if you want to regularly update your library.
The download might take several hours, as it can be hundreds of gigabytes in total.
An example of the end result.