The style will be basically whatever I come up with, generally mostly metal-influenced, but with elements of whatever other style I think would sound nice in the context, which can be pretty much anything

I'll probably include lots of ambient sounds because I think that's a good match for the space setting of the game.
So far, I've written a theme for the main menu, you can listen to a demo recording of it here.
It's not intended to be similar to the default main menu theme, but just something that in my opinion fits well.
I've also started writing Jupiter and Earth themes, inspired by the ones in the default theme, Earth will be busy and fast while Jupiter will be slow, very "ambient" and "empty". I'll post here when I have demos of these.
If you have any comments on what I have so far, please let me know!