Strategic Insights: Trading Games

by Shannon Appelcline

April 17, 2003 - A couple of months ago, when I was providing an overview of gameplay I touched upon a lot of different systems that you could build games around, including exploration, building, warfare, and... trading. The last, as it happens, is very near and dear to my heart because I've spent the last four or five months thinking about trading games: how they worked and how they don't — with the eventual intent of building a trading game of my own.

If you'd like to read some of the reviews I've written when considering trading games, I can point you toward my discussions of The Settlers of Catan, Fist of Dragonstones, The Settlers of Nurnberg, and Res Publica.

I wasn't really planning to go into depth on any of the gameplay types I'd outlined, at least not yet, but the last couple of trading games I played (Res Publica and The Settlers of the Stone Age, as it happens) really got me thinking about the lessons I'd learned, and so I decided that I wanted to do my best to lay them out, hence this previously unplanned article.

Defining Trade

At the most basic level, I think trade games are: games which involve transactions of limited resources in manners which are largely undefined in advance.

Let's break this definition down point by point:

• transactions means, essentially, trades. At least two people exchange something.
• limited doesn't just mean non-infinite, but more correctly limited within the scope of the game. If I have 100 foobar wrenches, and I know I'll never need more than 10 in a game, the resource is effectively unlimited within the scope.
• resources means items which have some value within the scope of the game. (Technically, I suppose, you could exchange valuations beyond the game — such as: if you give me two brick cards, I'll give you one ore card and sexual favors later tonight — but I'll just consider that beyond the scope of these game design articles.) These resources are most frequently interim tokens of some type, which are in turn used to buy other things within the game. The trading of high-level victory markers is much less likely because they'll usually be equally valued by all players (which I'll talk more about later).
• manners which are largely undefined is perhaps the core of this definition, because it makes clear the fact that trading is a freewheeling mechanic. You're not just purchasing where you know beforehand what you have to pay to get a resource; instead there's an open market where prices and values can freely fluctuate.

To offer a more concrete example:

Monopoly is a fairly well-known game which allows for the trade of an interim resource (in this case properties). The rules for it are very open: "Unimproved properties, railroads and utilities (but not buildings) may be sold to any player as a private transaction for any amount that the owner can get." However there is one particular stipulation: "However, no property can be sold to another player if buildings are standing on any properties of that color-group. Any buildings so located must be sold back to the Bank before the owner can sell any property of that color-group."

Players v. The Game

When you're thinking about building trade transactions into your game you can do it in one of two ways. On the one hand, you can have players do all trade interactions with the game system, and on the other hand you can have players do all trade interactions with each other.

The Settlers of Catan offers good examples of both systems. Generally trade is done with other players. For example you might have surplus ore and want bricks, so you put an offer out there. Someone says they'll give you wood for your ore, and you consider whether it's beneficial to you or not. However, Catan also offers a system-trade option where you can always turn four of a resource into a resource of your choice by trading with the bank.

So, which is better, trading with players or the bank?

By huge leaps and bounds, I'm quite convinced that the answer is "trading with other players". In fact, there's almost no comparison. By trading with other players you have the dynamic, undefined, unknown system that I said was actually the core of any trading system. By trading with a game, it's hard to create any type of dynamism unless you develop complex formulas for valuation that's based on what's been offered and what's being bought in the past — which might be possible in a web-based game, but will be almost useless in a tabletop game.

System-based trading also has the side effect that it can probably be gamed in a mechanistic, and thus boring way. My friends often jokingly call the original Traveller game "Merchants in Space" because of the fact that it presented system-based trading gameplay in a fashion that could easily be gamed. You found planet A which wanted resource from planet B and planet B which wanted resource from planet C and planet C which wanted resource from planet A and then you spent the rest of your gaming existence trundling between this triad of doom to very boring result.

Because you were trading with the system there was never any deficit in giving each planet the exact resource that it wanted, so you kept doing so. Ad infinitum.

Having said that trading with players is the best method to maintain sanity, let me take a step back and say that you should at least consider allowing trading with the system. The Settlers of Catan allows it for very good reason. The collection of resources isn't just an interim activity in Settlers: it's a fairly low-level interim activity. Other stuff (e.g., the building of various game tokens) depends upon the success of this trading, and you don't want players to fail at step A in a strategy game and thus never get to experience step B. For this reason Settlers of Catan offers a way to help yourself out even if your trading skills aren't up to par.

In Res Publica, on the other hand, the collection of limited resources is pretty central to victory in the game, and thus there's less concern with helping out players who can't manage to trade. They're going to lose, yes, but they're not cheated out playing a part of the game (actually, they can be in an early phase in the game, but I won't get into that detail).

The Core of Trade: Differing Values

Now let me reveal the mystical core necessary to make trade work in a game: your limited resources must have different values to different people.

That core idea might seem very obvious, but how to implement it within a game is a bit less so. Generally, I've seen three different methods used within games to ensure that each players values resources differently. The first one amounts to variations in "supply" and the last two to variations in "demand". They are:

Varying Allocations of Resources: The easiest method to institute varying valuation is to simply ensure that each player has access to a different set of limited resources. The Settlers of Catan does this by letting each player only start off the game with access to up to 6 hexes worth of resources. Generally only 1 or 2 of these will produce well. Since there are 5 different resources total that means each player will need to struggle to get three or four of them... resulting in trades.

One of the resource distribution methods that I'm considering for my own Merchant Kings games involves density loci of each resource being scattered throughout the galaxy. Therefore since each player starts off in a singular, discrete location he'll be forced to trade with other Merchants in order to acquire most of the other resources.

Partial Resources Requirements: Another important element for good trade is ensuring that every player doesn't need every resource in order to be successful. If, instead, subsets of resources are useful within the game, then players will be more willing to trade away certain resources depending on what their particular strategy is.

The Settlers of Catan again shows this rule off to good effect. Two core strategies in Settlers involve building roads, which requires brick and wood, and buying development cards, which requires grain and ore. Two players engaging in these two different strategies are thus likely to make mutually beneficial trades with each other.

Dynamic Valuations: Another way to allow for successful trades in your game is to ensure that different players place different values upon each resource in a way that's dynamically dependent upon the acquisition of other game components. This is sometimes done based upon map locations or some other method which can be easily seen. For example in The Settlers of Catan there are certain spaces which allow for trading specific resources with the bank at a 2:1 ratio, clearly increasing the value of those resources to that player.

Res Publica on the other hand dynamically varies value by using the common method of giving resources different values based on what resources you're already holding (Risk and the original Civilization use variants of this same method). In Res Publica you get to turn in sets of 5 identical resource for victory points, and thus you're inclined to collect cards that you have high numbers of and trade away cards that you have low numbers of.

Res Publica also manages to vary valuation by using a totally different technique: dynamic valuation changes over time. Early in the game, everyone is collecting "people" and late in the game everyone is collecting "technology" (because of the fact that technology produces more victory points than people, once you've hit critical mass of having enough people to trade technology, everyone that can does). This means that the valuations of these two general categories of cards slowly change as the game evolves. Similar techniques would be possible in a variety of games.

I should note that you don't have to use all three of these methods in order to differentiate values of resources in your game and therefore make trade run smoothly. However, if you don't use any of these methods, your trade game will probably fail, and that might even be the case if you only use one.

The Settlers of the Stone Age, the newest game in the Catan series, unfortunately makes this mistake.

There is varying allocation of resources in that each player only controls a set number of hexes of resources, exactly as I described in Catan, above.

However the idea of partial resource requirements, used well in other Catan games, totally fails here. There are two main paths to victory: exploration and building. Exploration requires furs and meat to create explorers, meat to move explorers and flint and bone to build up culture to allow better exploration. Building on the other hand requires furs and meat to create explorers, meat to move them, and bones, fur, and flint to create camps. Out of the four total resources in the game, all four are needed for each victory method, and they're all needed fairly regularly.

There's also not much in the way of dynamic valuations. Each player can purchase the same tokens with the same resources, and there are no spaces on the board which changes their valuations for any players.

There was some trading in the games of Settlers of the Stone Age that I've played, but it was very subdued and infrequent compared to the other Catan games, and I think that was primarily due to the fact that it limited itself by not increasing the likelihood of different players valuing different resources differently.

Ways to Trade

Thus far I've treated trade as a fairly general thing. The truth is, however, that there are a lot of different ways to manage trade within a game. I've outlined here what I consider to be the most important ones:

Free Trade: This is pretty much what I've discussed so far. Players can trade as they see fit, usually within some limited constraints (e.g., you can only initiate trades on your turn). The Settlers of Catan probably best epitomizes this type of trade, wherein the phasing player can trade within anyone he wants in whatever way he wants.

Limited Trade: From the core of "free trade" you can build any number of restrictions which limit exactly how trade works within your game. Often these are "rules" for how the trade may be conducted. Civilization, for example, lets you lie about one of the items you're trading. Res Publica on the other hand, places restrictions on what you can say when you're trying to make a trade (e.g., you're only allowed to offer a resource or request a resource; you can't offer one resource in exchange for another).

Free Auction: A free auction is usually a trade in which players make increasingly higher bids for an item and the highest one wins. For it to be a true auction, the winning of the highest bid needs to be automatic. If the trading player gets to choose, then you really have a trade not an auction on your hand.

Limited Auction: In a limited auction there are, once more, restrictions upon how the auction works. Most frequently this involves limiting the number of bids that an individual player may make. Sometimes these limits are based on sequence. For example, players may make their auction bids one-by-one, going around the table. In other cases, such as Fist of Dragonstones, all bids might be revealed simultaneously (in what that game calls a closed fist auction).

Dutch Auction: Though I've never seen it used in a game (and saying that I should note that there are probably a half-dozen games that I don't know about which use it), dutch auctions are another possible way to manage trade. In this auction you have "N" items for sale. At the end of the auction the top "N" bidders all get the item, for the sale price offered by the Nth bidder. So, for example, if there were 3 rare crystalline Ju Dogs, and the top 3 bidders offered $20, $18, and $12, each of them would get a Ju Dog for $12. People who bid less than $12 get nothing. (Some sources also use the phrase "Dutch Auction" to refer to what's really a "Reverse Dutch Auction", where the price of a resource is constantly being lowered.)

Seller's Auction: Some auction variants involve many sellers and one buyer, wherein the sellers are bidding on what they'll sell for (this is how most contracts are awarded). These often also involve reverse auctions in which a price starts high and gets bid down.

If you want to read more about auctions, I suggest the articles at agorics which cover a wide variety of auctions, some of which (such as the handshake technique) require a fair auctioneer, something which is tough in a tabletop game, but is very possible when you have a computer arbitrator in a web-based game.

So, which of these trading methods do you use? I think that's a personal decision that mainly relates to what you think works in your game. However, I personally believe that restrictive trading rules can allow for more interesting trade dynamics, and so highly suggest looking at how you can limit the ways that trading or auctioning works within your game.

Conclusion

And that concludes my thoughts on trade. As I said I wasn't really planning to write this article, and I currently don't have plans to write articles on other major gameplay systems, mainly because I haven't thought as hard about them as I have trading.

However if you think you have strategic insight into one of the other types of gameplay that I covered in my gameplay article (or a subset of one of those fairly wide categories), please drop me a line, as I'd be happy to carry a guest column by someone in the know.

And with that I'll see you next time.

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