Diaspora is a hardish science fiction roleplaying game with limited faster-than-light. The players collaborate to develop a Cluster of worlds, and characters are designed to have links both to the setting and each other. From the publisher:

Diaspora is a role-playing game that uses the FATE system to deliver a hard science-fiction framework for adventure, where you build the setting on top of the basic, gritty axioms of the universe: everything is bigger than you are. You will pilot spaceraft driven by fusion torches that light the night sky towards rifts in the fabric of space that shift you between a small number of lost worlds, each with thousands of years of history. And it's all yours.

Although Diaspora is based on FATE, it is a complete game requiring no other purchases to play. You will need dice, pen, paper, and friends, but all the rules you need are right here.