Port Royal, in spite of its big box and extra bits, is really just a trick taking card game like Rage or Trumpet. Instead of taking tricks to score points, you take tricks to earn cargo cards to put on your ship. But these cargo cards are then used to score points later, so it's just one more level of indirection.

The player who leads chooses one cargo card that you are playing for, from a line of face-up cargo cards. He then leads the trick. The freeform part is that you never have to follow the suit led. In fact, the only restriction on card playing is that you can only trump if you don't have a card of the suit led. Otherwise, you can play any card on any trick.

The player who wins the trick places the chosen cargo card into the hold for the type of cargo shown on the card. This is generally good, except that each hold has a maximum capacity, and if this is exceeded, you will score zero for that type of cargo at the end of the game. There are also some special cargo cards that can be any type of good, or subtract from the quantity of goods, or enlarge the size of one hold.

Trump is chosen by high bid, and you can use one cargo card, earned this round, to offset the amount of your bid. There are also two cards that negate trump, but only during the trick in which they are played.

I wasn't too excited by the game, as I'm not wildly thrilled by trick-taking card games, and there are several better trick-taking card games already out there. (Such as the aforementioned Rage.) Even those people in the group who were big fans of trick-taking card games were frustrated by the game, since such strategies as drawimg trump were negated by the rule that you don't have to follow the suit led. It has some nice concepts, especially the cargo that you want at first, then don't want as your holds get full. But there's not enough to raise it above the level of a mildly interesting card game.