The three sisters is a sustainable farming system developed by Indigenous peoples in North America. The three sisters, corn, beans, and squash are planted together, each supporting the others:

• Corn: Provides a strong stalk for the beans to climb.
  
• Beans: Fix nitrogen in the soil, fertilizing the crops.
  
• Squash: Shades the soil, preventing weed growth and conserving moisture.

This symbiotic relationship is a great inspiration for designing a currency system in Eco by Strange Loop Games[play.eco].



Garlan Miles, CC BY-SA 4.0 <https://commons.wikimedia.org/wiki/File:Three_Sisters_4.jpg>, via Wikimedia Commons

The first part of this model is about creating a common currency. This is a core aspect of the model and is represented by the corn stalk.

While early experimentation with individual currencies can be beneficial for learning to plan a good store, a unified currency simplifies transactions and fosters communities.

Don't cheat minted currency. Consider a collective agreed-upon currency instead. The "Chief's credits" works very well when players naturally adopt the currency of a natural leader or the admin. In fact, discussing this idea is one more reason to hold a session-0 before the server opens.

Now that we have a common currency, the second part is distributing it in a meaningful way.

There is more here than simply giving the money. In fact, a common mistake is to arbitrarily distribute the currency to all citizens. In this scenario, citizens are clueless because they still don't know if a tomato is worth 1 or 100 credits. Without a common reference, you may be creating a very frustrating event on the server.

"They're you go kid. Now do something with it"

So money distribution is first about finding means to establish reference prices for basic resources (wood, clay, rocks, plants) to create a stable market.

A quick way to do this is to make a store which buys basic resources and crafted items to make the first town hall. This way, your future citizens receive money in exchange for their contribution and the prices act as a reference.

If you are lucky enough to play with a small group of friends, you can go further and agree to a reference sheet[docs.google.com] in order to detect attempts at dumping and exploitation in the future.

Second, currency distribution is a key element in keeping your citizens busy and motivated. Servers that rely on trade between individual players are eventually weakened due to local bottlenecks, clusters, protectionists measures and other natural phenomenons.

Government spending through a town hall store and contracts provide opportunities and allow you to strategically stimulate economic activity. This is especially great for newcomers or players who feel left out when their skills are temporarily less useful.

We have our strong stalk of corn with a unique currency. Next our distribution system is the beans winding around it and providing good opportunities to get the currency and keep players motivated.

After a few days, you may notice trade slows down again as people with a lot of money seem to lack the motivation to sell items. Luck, experience, skills unbalance, dumping, exploitation tricks and other factors are creating inequity and it seems the money you distribute is not doing much good anymore. In fact, it may well be hurting the economy.

"Weeds are coming, we need to squash them !"

This is where the third component is useful: money flows back in the treasury of your town.

Eco offers a variety of taxation systems to fill that component. From the basic tax on sales available with the government table, you can explore creative solutions using laws: tax based on land, income, wealth, value of housing, etc. I am a huge fan of wealth-based taxes in Eco because of the way it slows downs competitive and over-enthusiast players and make them create more opportunities for players who struggle (progressive wealth tax available in my playbook[sites.google.com]).

But, there are others means to fill the treasury. Most public services can have some income (ex.: selling scrolls at the research centre or a fee for storing taillings at the public dump).

You may also encourage public-private partnerships to fund projects and services (ex.: personal storage in a fablab). It's time to be creative as long as it doesn't ruin the fun.

"Money cycles without taxes are still interesting, because this is a way to detect players who created money traps with their store (high profits, reduced opportunities to provide basic resources)"

Here's a practical example of how to implement this model:

• During session 0 before the server opens, designate a leader for your town and adopt their currency from the start.
  
  
• The leader quickly makes a store and begins to buy basic resources to build the town hall and launch early research. Roads, fablabs, hotel, energy towers and other projects and distribution ideas will follow. Some players receive money to organize and fund the projects themselves (early ministers).
  
  
• Quickly vote a progressive wealth tax:
  
  4 times per day, tax each citizen based on a percentage of their total wealth. This percentage is calculated using the total wealth divided by X, where X is a factor that depends on the value of currency and the strength of the tax you want to create. I used x=500 on stable worlds where wood logs are worth 1 credit and where we planned a starting pool of 2000 credits per player. To see how this tax behaves (and change numbers), please look at the resources in my playbook[sites.google.com].

This guide proposed a general system to handle currency with three parts:

• Common currency
  
• Active currency distribution
  
• Currency return

There is a sheer abundance of options and tools to use in Eco, but this models offers a generic structure upon which you may build a thriving town. I bet you will also quickly notice how you can use these components to make essential adjustments to the economy, such as reducing inequity and help mitigate skills unbalance.

I am a player of Eco since 2018 and evolved in a variety on contexts: competitive, collaborative, communist (weird label), heavily modded, etc. I now only settle on vanilla worlds with medium settings and heavy emphasis on collaboration. I am a professional in the field of collaborative learning and a bit less novice everyday in quality management and writing in English.