One line early in my Westphalia teach always gets a laugh, and it's this one: There is no money in this game, only Debt, and you don't want it but you only ever seem to get more of it. Sometimes, but not always, I get a second laugh when I explain that Prestige reduces the rate at which the interest on your Debt accumulates, "kinda like a credit score".
(Sometimes the laugh is tinged with a streak of bitter recognition - what better way to get away from thinking about my mortgage and my student loans and the fact that I'll probably never get out from under it all for a couple of hours, than playing a game that reminds me of it constantly, thank you so much Tom.)
More than just my weird idea of a joke, the Debt mechanism in Westphalia is an integral part of the design. Everything that you accomplish to advance your position in the game has the potential to reduce your Debt at the end of the game. Possession of territory, being party to a trade agreement, et cetera. And every player's victory condition - and each of the six player positions has its own victory condition - is measured against their remaining total Debt. The Dutch Republic, for example, needs to have made trade agreements in excess of their remaining Debt; for Sweden to win, their total Debt must be less than the sum of their own territorial gains plus the Tolerance that Austria has granted to Protestants in the Holy Roman Empire.
Besides trying to accomplish and accumulate things that will reduce their Debt, players need to control the rate at which that Debt accumulates. How this works is that at the start of every Diplomacy Phase, the players gain Debt depending on their current total Debt. If someone has between 20 and 23 Debt - let's say they have 21 for the sake of argument - they will accumulate 6 more Debt. On the following turn, their 27 Debt is going to put them into a new bracket where they will accumulate 8 additional Debt, and holy cats, that's a lot of Debt.
Now, this rate is decreased according to a player's current Prestige. If I have 21 Debt and 3 Prestige, for example, I'm only going to accumulate 4 Debt (instead of 6), and if I go into that next turn with 25 Debt and still have 3 Prestige, I'm going to gain 5 Debt (instead of 8). This relationship between Debt and Prestige gives players two incentives: one, to keep their total Debt as low as possible, and two, to get their total Prestige as high as possible.
Prestige, like pretty much anything else in the game, can be traded. This is helped along because the "interest rate" reductions are tiered: you accumulate the same exact amount of Debt with 4 Prestige as you do with 3. So you might be willing to give up a point of Prestige, to go down from 4 to 3, as that doesn't immediately hurt your position - provided they give you something that's worth the trouble. Prestige is primarily gained by winning a battle, which gives players some added incentive to go campaigning. Prestige is also lost by losing a battle, which gives players some added incentive to exercise caution. I'm not going to get into the details of the military aspects in this piece, except to say that these two opposing impulses - the reward of gaining Prestige and the risk of losing it - contribute enormously to the cat-and-mouse, feints-and-counterfeints tempo of operations.
Players are more likely to trade Debt than Prestige, though, and that probably sounds counterintuitive: if the whole point is to reduce my Debt at the end of the game, and if having more Debt during the game increases the rate at which the interest accumulates, why on earth do I want to take on someone else's Debt? Well, you don't! But you'd be happy to let someone else take your Debt, and maybe if they want something from you - this piece of territory, this adjustment to the Tolerance track, this trade agreement, this promise not to attack you this turn - you make the transfer of that something conditional on them taking on some of your Debt. Naturally, you might find yourself on the opposite end of the exchange. In fact, in practice, very few trades in the game don't involve some shifting of Debt.
The Thirty Years War is often seen in confessional terms, and though those tensions inflamed the passionate and provided a convenient pretext for the opportunists, my game aims to view the causes of the conflict largely through an economic lens, as all those causes - territorial ambitions, pursuit of local autonomy, international reputation, power politics, and even confessional identity - are, in the end, about money.