I wonder how hard would be to port it to linux. Maybe dxvk may help? Also, latest version is from 2016, so it looks like software that doesn't brings any money is finally open source because there is no hope to make any in the future. I'm sorry for them but glad they open sourced it. Would love if outcomes like this happened more often.
Orbiter never tried to bring in any money. It has always been a one-physicist pet project (first version published in 2000), closed-source albeit very open to all kind of mods and featuring a vibrant community.