Phew, I'm happy it works on mac~
There is no end goal because I couldn't come up with a meaningful one other than like self-decided goals of discovering all planet types or gathering all artifacts – it's a very samey game, really. Maybe the game could open up more or like have an end-game-dialogue after the four artifacts but still let you continue exploring?
I've actually thought of letting people name undiscovered planets and stars (because the galaxy is deterministic, actually) and maybe have some ranks or something based on that? Also allowing people to visit the surfaces and take "photos" that could be attached as "postcards from the edge" to a central database thingie… I've actually had a lot of ideas, but 72 hours is not a lot :p
I'm really happy you like the scientific aspect, I have plans to add much more of that – fun fact: the star types are distributed almost exactly like in our own galaxy, and the apparent magnitude/visibility of stars is accurate to 7 decimal places :D there's a lot of scientific accuracy to build on, really…
I'll definitely have to check out the nasa website and see if I can't make something like "space engine but with a purpose" or something. Really happy to hear you enjoyed it and want more – I have plans!