Peace has finally come to the war-torn Central Galactic System, united into a single federation by the Imperial Forces of Galactica (see Galactic Empire - from Broderbund Software). The end to the fighting has cost you your job as Commander of Galactica's Imperial Forces, but it has simultaneously opened up new opportunities in trade for the person with the vision and ambition to exploit them.
You once commanded a fleet of hundreds of ships. Today you have only one. You led armies of millions a short year ago. Now you pilot your single ship alone, aided only by two loyal comrades who remember what you were and have faith in what you may become. Navigator Kirman of your old starship refused an opportunity to join Galaco, the interplanetary rocket fuels cartel, and elected to come with you. Even more surprising, Computer Central, the heart of your starship, stuck by you. Perhaps its judgment has been clouded by emotions after all, as Major Bayliss alleged.
The principles of trade are not difficult. The farther a product is from its world of origin, the greater its value. All one has to do is buy or trade for cargo, take them farther from their home world, and trade them for other commodities. In practice it is not that simple, of course. You don't know the place of origin of the products, at least at first, nor is anyone likely to tell you. Until you develop experience on each planet, you don't know the rates of barter there, and the locals will try to exploit your ignorance by fleecing you if they can. All your experience can be worthless, too, if you are so incautious as to ply one route too often, for the largest trading firms keep their ears open, and they have the economic muscle to deal you out of any route that appears too attractive.
There are other problems as well. You will find that no trader will accept the coin of the realm except on Galactica. On every other planet, barter is the medium of exchange. Your credits are only good at the fuel depot, and even the cartel will barter for commodities if you are short of cash (they are particularly extortionate when they feel they have you over a barrel, however, so it is generally better to buy fuel with cash). Local rates of barter can be hard to discern, too. If a local trader thinks you are asking too much for part of your cargo, he may refuse to discuss barter of that item any further. That can be expensive, when one considers the cost of bringing those goods to his doorstep.
Your most important cost consideration is fuel. The ship is powered by microscopic fusion modules, sold across the galaxy at the fixed price of 2 credits per millit. The amount of fuel you need for a journey depends both upon the total mass of ship and cargo and upon the distance to be traveled. Fortunately, Computer Central is an old hand at these calculations and can be relied upon to do much of the brain work.