Yes, I want to signal boost this along with "everyone" else. I have played this original game system and really enjoyed using it to run my first satisfying role playing game of sci-fi.
CT-ST_Starter Traveller is an introductory version of the game. It included a book of core rules, a separate set of charts, and a book of adventures (there are three separate download files). Now all for free in PDF over at Drivethru.
The adventures are forgettable, but you want this for the core system and Marc Miller's recommendations for use. That being; a game system for those who want to run their own vision for an interstellar game universe. Yeah there are the typical conceits which have come to define Traveller; jump ships, death during character creation and massive computer space required during star ship build, but as a flexible referee world-building tool kit with a solid, thoughtfully built personal combat system I don't find much which beat it.