You can play it in Singleplayer Campaign with a story, or OpenSP mode where you just fly around with a bada$$ ship and do what you want. The mod even makes the AI better and the game (like the name) more balanced. And there are plenty of different cargo types that you can sell at different ports for different sums, all easily explained in the game. to upgrade on each ship in hundreds of thousands of possibilities. Plus you get guns, engines, shields, thrusters, missiles, torpedoes, mines, repair droids, radar, tractor beams, etc. And even more, some I don't even know from where. TV Show ships like Babylon 5, Battlestar Galactica, and Star Trek and even from movies like Star Wars. Videogames ships like homeworld, wing commander, dark forces, and tachyon the fringe. There are hundreds and hundreds of ships that you can fly from almost everything you can imagine. The Rebalance Mod, made by Michael Dan with hundreds of contributors, takes all those aspects and cranks it up a notch or two(xthousand).
Very easy to control (you can actually use just your mouse if you want), simple trade system, and fun space combat sim. I use to have it listed in my sig, but I changed it recently so you might not have noticed. Well then, that would make me wrong, wouldn't it.