Usually people used to launch Freespace 2 with the SCP new FSO executables either by adding commands line to the shortcuts when you knew what you were doing or using a launcher to easily configure things.
With new releases and versions of the FSO executable old launchers weren't compatible anymore, and so came Knossos
Knossos is an open source launcher and a mod/FS engine game manager all in one :
https://www.hard-light.net/forums/index.php?topic=94068.0As you can see in screenshot it has a modern interface too in comparison to launchers of old.
But why i mention it on this thread is that even if you don't have Freespace 2 (and missed the GoG free offer) you can still use Knossos to download, configure and play the standalone fan games made with the FSO .
Wing Commander Saga is truly excellent, The Babylon Project has some good stuff for B5 old fans , Diaspora and Beyond the Red Line are great Galactica games, and there are more of those standalone games (but not tried myself so i can't say much about the other games)
Note : in window 10 the Knossos installer will trigger the SmartScreen thing because the installer is not signed (happens regularly with open source stuff), but you can ignore it without problem.
If you don't want to use the installer, you can just extract the installer with something like 7zip and launch the knossos executable (it will not trigger SmartScreen this way)