A very engrossing and very deep 17th century economic simulator. You start as a small time trader with a small ship, a warehouse, and a purse of gold. From there you buy goods cheaply at one port and sail off to other ports and hope to find one that will buy those goods at a high price. Once you obtain enough capital you increase in rank. Rank increases allow you to hire more captains to have separate fleets, and obtain more building permits in different ports.
The economic depth is amazing. Each port is capable of producing 5 different goods. Some goods production is dependant on having a supply of another good, and that's where you the trader comes in. Do you want to buy rope from Port A? Then they need a good supply of hemp from Port B. Furthermore, once you obtain a building permit in a particular port you can become a greater part of the local economy by building your own warehouse and then manufacturing facilities. If you are smart enough and have the gold you can buy basic crop plantations in one port, produce that good cheaply, haul the goods to your advanced manufacturing facility at another port to cheaply produce the finished good and sell it for a massive profit. For extra profit you can also build housing for the new workers for your faciliteis and have them pay you rent. You also make money buy shipping in surplus workers from other ports to the port that now needs those workers.
Not that there aren't plenty of obstacles to stand in your way. When the game starts out in free play there are no pirates active and no nations are at at war. As the game progresses the four nations, Spain, France, England, and the Netherlands can and will end up at war with each other. You can attempt to stay friendly with each nation and continue selling to all sides or offer to help one side over the other by raiding ship, blockading ports, and attacking ports. Doing so rewards you, but at the cost of not being able to do business with the other nation until you repair your status with them.
Piracy is your other main concern. Pirates start off weak, with a single ship, but quickly grow to a major problem. They will sack ships, and invade ports. The sacking of ports is of great concern if you have a warehouse in that town as they will steal all of your stored goods, otherwise it is a great opportunity to sell the newly ravaged port fresh supplies. You can mitigate the risk of having your favorite port raided by pirates and enemy nations by donating cannons and paying for soldiers at your personal expense, and it is VERY expensive, so don't bother until you are wealthy and have something worth protecting. You could try to kill the pirates, but the game will not let you attack the pirates base until it randomly shows up on the map. Once you do know the secret location you must have a both a massive (expensive) battlefleet and a letter of Marquee allowing you to attack them. Why you need permission to kill non-Marquee Letter holding pirates is a bit of a mystery. That is about as historically accurate as all the white guys who work on your sugar plantations that you pay wages to.
While the game is incredibly deep, it suffers from having ZERO in-game help or tutorials. It took me three full days of playing to realize I could have my warehouses auto-buy goods when they were cheap so that I didn't have to micro manage them. The same is possibly with your trade convoys but I haven't been able to fully figure it out yet. Finding an online guide is a must for full enjoyment.
There are even deeper aspects of the game and economy, but it would take a book to get in to them all. If you are a lover of deep economic sims this game is 100% for you.