Trades of Qud

Caves of Qud banner art

I’ve been playing a bunch of Caves of Qud, a science fantasy roguelike, and at one point in the trading menu I had to pause because I was so surprised by a simple mechanic. I really wanted to emulate the feeling in my upcoming RPG, so this blog post will try to encapsulate some of the ideas I have in my head for now.

Exchange and Encumbrance

So how does trading work in Qud?

Central currency of Qud is fresh water that is measured in drams. And water has weight! Characters can only carry up to their weight limit in the game. Because of this, arises an interesting problem.

It is not efficient to carry lots of universal currency.

Rather, you want to carry either actually useful objects (weapons, artefacts, tools), or items of high value and small weight (gems).

Mausritter has that implemented already to an extent. You can carry a purse which takes up an item slot, but can only contain up to 250 currency. So if you want to optimise, you are much better off carrying an item that’s worth 250+. The problem is that it will be hard (or impossible) to use for small purchases, but it’s efficient if you are transporting lot’s of valuables from place to place. For example a merchant might want to spend as many pips as possible on high value/one slot items that are easier to transport, and can still be exchanged for pips at the destination.

When I was playing Caves of Qud, I came back to the settlement to sell the treasure I had… but then realised that I would be carrying so much currency in water that I would be overencumbered. So I had to make a decision on the spot. What items do I actually need? Where else can I trade these items? And this motivated me to embark on trips that I probably would not have taken otherwise.

So how can we implement a more involved approach to commerce in RPGs?

Ideas for Games

Trading items for items (barter system). Pretty self explanatory, but removing currency changes how the game functions in several ways:

  • No classic advancement/goals. When you have universal currency, it is a good measure of how well your character is doing. Accumulating gold is the goal of the game and is proportional to levels in most of OSR games. Without some coin, you will have to look for alternatives for the players to pursue (maybe it’s making discoveries or making faction relationships for example).
  • Simplified, yet more thoughtful trade. Without currency, you don’t have to calculate your expenditures. Now your choice lies in deciding what item is worth giving away for another. Is your trusty sword really worth the new bow? What about the ancient relic that the merchant wants to get rid of?
  • More pressure on the referee. Important to keep in mind that the GM will have to decide what is an equal trade and what isn’t. This can easily get messy if the players disagree. So if you are planning to add a system like this in your game/adventure, be sure to provide tools that help with settling deals. One example could be a random reaction table for the merchant, or an easy tiered system for items.

Doing quests and favours. You can get the item, but only if you complete a certain task. This is not new and has been done many times before. This is the classic NPC who need something done more than any currency (kings, wizards etc.). This will probably get exhausting for every little item the players wants to trade, but effective for high value stuff that the party really needs.

Making use of stats. A social stat can now not only be used to get better deals, but also to find merchants, figure out what they value most.

Resource trading web. If we consider that each resource has a different value in different location, we can create interesting connections between settlements. This also gives the players a motivation to travel more to find the right place for trade.

For the game I’m writing I will be giving resources 3 tiers:

  1. Common: something that the region is rich in and ubiquitous enough for trade. However each item doesn’t have much value.
  2. Rare/Need: a practical resource the region needs. Can be wood, stone, metal etc.
  3. Luxury: an object of desire that is hard to come across. Silk, wine, seashells, jewels.

And every settlement has either different resources, or different distribution of them in each category. So in a river town for example, water does not have a lot of trade value (common), but in the desert village, they will gladly accept it (need).

This also made me realise an interesting detail in Caves of Qud. All the merchants are stationed in the desert (presumably because the area gets lots of pilgrimage traffic), but what if they are also there to increase the value of the water currency they carry? (of course this is not how the game works, but would be kinda cool.)


More rpgs that have cool trading systems:

Heart: The City Beneath has a system that allows you to trade items for other items of the same rarity. Objects are ranked in how common they are to come across. The rarer it is, the more common items it takes to exchange for.

Stonetop gives settlements a prosperity value that decides what items are available to the PCs. The more prosperous a settlement is, the more valuable items it has. There is a more detailed tier system for objects that goes from 1 to 10 (less valuable to most valuable), and it depends on the settlement region.

Apocalypse World has an abstract barter move, which you can use to find the items you need. If you roll well, the deal is done. If you roll worse, you might have to pay more, exchange for another item, do a favour etc.

Vaults of Vaarn issue #2 introduces the city of Gnomon, which uses water-debt tokens as a form of evaluating goods. More often however, items are traded based on their slot size (1:1). If the GM is uncertain whether the deal can be made, there’s a reaction table for merchants that is modified by player’s EGO. Results are anything from inciting a violent fight to receiving an extra gift.


And that’s it for this post! Not very ground breaking I know, but I think it’s a neat topic to ponder. Let me know if you have any ideas about cool trading options in rpgs on twitter or discord. Happy holidays!

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Further Reading

Caves of Qud Wiki - Trading - if you want to dive in how Qud’s trading system works in detail.

DIY and Dragons - Roguelike advice for tabletop games - not trading related, but I love how this post explores implementation of roguelike concepts in tabletop.

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