bartgesang: I just recognized, that System Shock 2, the Thief series and some other games in my catalogue do not list Windows 7 as supported OS anymore. I bought this titles way back before 2020 and this was never an issue back than. Does that mean, I can´t start them on my W7-system any longer?
If you downloaded and backed up your games back when you bought them or before GOG updated them for new Windows OS, you should still be good to go, if you have those backups.
However, if you are downloading them now, you might be out of luck. It probably really depends on if and how GOG might have updated the games.
Official support for Windows 7 is no longer, but I've found that even Galaxy will run on Windows 7, despite them claiming otherwise ... at least that was the case about a year ago ... not talking about earlier v1.x Galaxy.