Originally Posted by Passacaglia
Sure. Each card has a point value, that corresponds to what deck you drew it from.
1 = Hides and Ochre
2 = Iron and Papyrus
3 = Salt and Timber
4 = Grain and Oil
5 = Wine and Cloth
6 = Bronze and Silver
7 = Spice and Resin
8 = Dye and Gems
9 = Gold and Ivory
Now, the more cards you have of each type, the more it's worth, somewhat exponentially. The formula to determine how much your set is worth is:
number of cards in the set squared x point value of the card
So if you have 3 Grain, it's worth 3 x 3 x 4 = 36. Note that we only count grain here, not oil. So the idea is, in order to make your hand worth more, you don't want a Hides, a Papyrus, a Timber, and an Oil (10 points total). You'd rather have 4 Papyrus (4x4x2=32 total). That's where trading comes in.
Another note about the cards, each deck contains calamities. These are bad, and you don't want them. Some calamities are tradeable:
4 Slave Revolt
7 Civil Disorder
8 Iconoclasm & Heresy
Some are not, and if you get them, you're just stuck with them:
4 Civil War
When you trade, you must trade at least three cards at a time. Obviously, no one will want to trade with you if you have a calamity, so it's okay to lie -- however you must tell the truth about at least two of the cards. The site lets you do this -- when you make trades, a "lie" button will pop up, letting you claim that card is something else. Obviously, you'll lie when you trade calamities. Note that if you use "unspecified" when lying, this basically means that you're acknowleding that that card is a lie, which means you have to be telling the truth about the other two. This is good because if I want Bronze from you, and you trade me Bronze, Timber, and Iron, but the Bronze is the lie, that really screws me. But if you give me Bronze, Timber, and Unspecified, I can accept the possibility of receiving a calamity from you, as long as I know I'm getting the Bronze.
Hopefully that helps! Feel free to ask any questions if it doesn't!