You are basically in command of a large ship (over a dozen to choose from, ranging from cruiser to supercarrier, with a wide variety of equipment, from fighters to cloaking devices), in service of one of over a dozen different races and various factions. Would you be in service of Terran/ Galcom, Terran Insurgents, or other combinations?
Once you have your ship, you can travel among dozens of star systems, hundreds of planets and moons, and land on those that you CAN land on. Trade commodities at the various star stations (that are friendly or neutral to your faction), buy up more fuel and weapons, and perhaps upgrade your ship. Fight off enemy forces (could be raiders, insurgents, or just hostiles), give orders to marines to fight off armed intruders. Control shuttles and/or fighters (including towing, retrieval of jettisoned cargo, etc.). Capture enemy ships and send them to a star station for reward. Take control of one of the over 60 different crafts in the universe (your ship is merely one of them). Mine planets and moons for minerals (which can be sold for money). Exit the craft in first person (in space or on the ground) and fight/move in first person, including use of ground vehicles... If you can think of it, this game probably has it.