>>96011020
Here are 3 options
>Traveller
If you want slightly harder sci fi were you deal with more mechanical problems and world creation and character creation and stuff. Doesnt have to be super hard sci fi, just slightly on the more firefly/battle star galactica side. cowboy bebop side. 2d6 skills based.
>west end games star wars d6
Slightly more on the puply side, bit quicker to get started and good for more quick paced action and adventure. d6 dice pool
>Stars without number
if you are a dumb dumb who only knows how to play dnd. Fine system that combines dnd's base d20 roles for combat with travellers 2d6 skill system. has a lot of GM tools (which traveler does as well)