Traveller
The first science fiction RPG¸ this is set in a large intersteller human empire (""The Imperium"")¸ competing with other human strains (the psionic ""Zhodani"" and the Earth-derived ""Solomani"") along with select alien races (the wolf-like Vargr¸ starfish-like Hivers¸ and lion-like Aslan). It is a mix of hard sci-fi with isolated space-opera elements: notably psionics.
The mechanics change greatly between editions. The original and second editions (currently being reprinted by author Marc Miller's Far Future Enterprises) have d6-based resolution -- generally roll 2d6 under a target number. Character creation uses a random-roll lifepath generation. The 2nd and 3rd edition converted many of the rules over to the GDW house system. The fifth edition from Mongoose also has separately-published settings including a ""Judge Dredd"" setting and ""Strontium Dogs"" setting (based on the British comics series). - A description from https://darkshire.net/jhkim/rpg/encyclopedia/ with kind permission of John H. Kim"