http://www.spacebasedf9.com/

Double Fine abandoned DF9 long ago, then released it as is, the game will never be finished.

Go look up headlines like "Spacebase DF-9 Development To Cease, Game To Release"

If someone else wants to make a game  with the same sort of gameplay, you let them. Honestly the visuals aren't even the same.

Not everything that is a space base building game is DF9, which has been abandonware for a very long time.