I'm one of the 5 poor sobs who still plays darkorbit, and someone on github made a linux native launcher available as an appimage. I don't recommend playing it though, because aside from the community becoming smaller and smaller, the game also runs like ass even on a high end system (not because of the unofficial app, but because of the game itself), and it has this issue with it taking up more and more ram over time, and it has been like that for over a decade now. Also a lot of server issues lately. The devs don't seem very interested in improving the game.