Set the compatibility to windows xp, service pack 3, then select "run in 640 x 480 screen resolution" . You can do this by selecting the change settings for all users button.

Modifying sfc.ini was enough to get the game running on Windows 11; setting async to 0 kept it from crashing. No compatibility mode necessary.

If you are still having trouble, make sure to run the video settings panel before launching the game to ensure that your primary display device has been selected. (In Galaxy, right-click the game, select additional executable, and then select Video Settings; otherwise, run config.exe in the game's root folder.)

I just purchased the game on GOG. It works 100% without ANY configuration on my Windows 11 laptop.

The version on Steam does not work well despite multiple configuration attempts.

Just the opposite for me on Windows 11. Coul dnot get the gog version to work, but was able to get the Steam version to run.
But, yes, gog needs to fix it, since so many people have problems with it.