Plane Sailing
Astral Admin - Mwahahaha!
Classic Traveller is still in print. And, going against the grain here... the original 3 books (called the "3 LBBs" or 3 Little Black Books) are nice because they predate all of this stuff about the Imperium and the enormous body of canonical setting material that has come about.
In the original 3 books of Traveller (also published as The Traveller Book in a single volume, or Starter Traveller as a boxed set) posit a sci-fi setting where laser weapons require backpack power sources, where the largest possible ship is 5000 displacement tons and the setting is whatever you want it to be.
That is the traveller that I started with - I was quite surprised when they brought out all that 'Imperium' stuff, because I'd already got my little cluster of planets and campaign world statted out by the time things like the uninspiring 'spinward marches' appeared.
I was always a little frustrated with traveller in the early days, because I wanted to play 'star wars' as a sci-fi game, and traveller just didn't match that... but it was the only sci-fi game around at the time!