The game is not available except by installing Galaxy. Galaxy is never supposed to be required for anything. Galaxy's installation is very poor, and is the first time I had to use CCleaner to delete a broken installation (registered but not present), after I had manually downloaded both the 32- and 64-bit dlls it required.
After the hours I spent hunting for that fix, the game really doesn't hold up outside the environment of Witcher 3. It just isn't as good as other digital CCGs.