We are using the GURPS 4th Edition ruleset.
PCs will be built using 60 points.
Tech Level is 10.
Psionics can be bought at character creation. GM can help work through the rough spots.
Magery can be bought at character creation.
Radiation and hard vacuum are serious space hazards.
Most places are not at war and are civilized. Wearing heavy armor and sporting weaponry in the open will be frowned upon and might even be criminal. Plan accordingly. Legality classes and Control levels do interact. They can be viewed on page 506-507 of the Basic Set: Campaigns. Most places that are not in open warfare will operate at Control Rating 3 or 4.
Spaceships can travel between the stars and space is big, like really, really big. Even so, planets themselves are huge. Despite having orbital supremacy in most cases, what lies behind the next rise can, and will be a surprise.
More to come.