The One-City Challenge (OCC) in Civilization VI isn’t just a self-imposed rule; it’s a total rethink of how the game is played. It changes the usual empire-building story into a sharp, focused puzzle of optimization and deep strategy. Every choice, from your starting spot to your final project, becomes incredibly important. In this high-pressure environment, most civilizations just can’t keep up, as their main advantages in expanding become useless. However, a special few don’t just get by; they flourish. Their unique abilities fall into place perfectly, letting them build a massive single city that can stand up to and defeat the whole world.
This guide is all about the top three civilizations for winning a One-City Challenge. These aren’t just civs that can manage; they are powerhouses perfectly built for playing tall, each giving you a clear and strong way to win. I’ll break down their strengths, give you clear, step-by-step strategies from the first era to the last, and show you the real examples you need to make one city a world power. Forget about big empires; real strength is in perfection.
Portugal: The Unbeatable Gold-Making Machine of the OCC
For the One-City Challenge, you have Portugal, and then you have all the others. I’m not kidding when I say that João III’s Portugal is the most powerful and steady civilization for this way of playing. Their abilities don’t just work well with a single city; they seem made to completely ignore its limits. The main problem in an OCC is getting things built. With only one city, making districts, wonders, and units is a slow and tough job. Portugal fixes this basic issue with a simple and smart solution: they make so much gold that they can just buy their way to victory.
The Portuguese Way to Amazing Wealth
Portugal’s power comes from its special leader ability, Porta do Cerco, and its civilization ability, Casa da Índia. Porta do Cerco gives you open borders with all city-states from the start and, even better, a trade route for every civilization you meet. In an OCC, you’ll meet every other civ, which means a huge number of trade routes from your one city. Casa da Índia makes this even better by boosting the income from these international trade routes by 50%. The money starts as a small flow and soon turns into a huge flood.
Your early game with Portugal is all about unlocking and getting the most out of these trade routes. Your first district has to be a Commercial Hub, then a Harbor right after. Your first builds should be something like: Scout, Slinger, Builder, Commercial Hub, Trader. Once that first Trader is ready, send it to the farthest city-state or civilization you’ve found to get the most gold at the start.
Real Example: Let’s say you’ve met five other civilizations and three city-states by the Classical Era. With the right policy cards and buildings, each of those eight trade routes can easily bring in 10-15 gold per turn. That’s a basic income of 80-120 gold per turn before anything else. By the Medieval or Renaissance Era, with wonders and policies that boost trade, this can easily become over 500 gold per turn, letting you buy a new building or unit almost every other turn.
How to Play: From a Coastal Start to Ruling the World
Where to Settle is a Must: You have to settle on the coast. No matter what. Your Harbor is just as important as your Commercial Hub. A coastal city with some sea resources and a river for the Commercial Hub’s extra bonus is the perfect start.
Early Game (Ancient to Classical Era):
- Focus on Exploring: Your first Scout is key. You need to meet every civilization and city-state as fast as you can to get more trade routes.
- Key Techs and Civics: Go straight for Celestial Navigation to unlock the Harbor and the Mausoleum at Halicarnassus wonder. Then, go for Currency for the Commercial Hub and its buildings. In the civics tree, rush Foreign Trade for the extra trade route and the very important Caravansaries policy card (+2 Gold from all Trade Routes).
- Building Wonders: The Mausoleum at Halicarnassus is your first big goal. The extra science, faith, and culture on all coastal tiles is a big help, but the best part is the extra charge for Great Admirals and Engineers, which you can use to rush important wonders later. After that, Kilwa Kisiwani is the most important wonder for any OCC game, and for Portugal, it’s a game-changer.
Mid-Game (Medieval to Renaissance Era):
- The Power of Kilwa Kisiwani: This wonder is your main goal in the mid-game. If you are the suzerain of two industrial city-states, Kilwa will give your capital a 30% boost to production. If you are the suzerain of two scientific city-states, it’s a 30% boost to science. For culture, it’s a 30% boost to culture. In an OCC, these percentage bonuses are huge. You’ll have the gold to stay suzerain of any city-state you want, making Kilwa’s bonuses a constant part of your plan.
- Governor Pingala: Your go-to governor is Pingala. His Grants promotion (+15% Science and Culture) and Connoisseur promotion (+100% Great Person points) are vital. Put him in your capital and promote him all the way as fast as you can.
- Owls of Minerva: If you’re playing with the Secret Societies mode, the Owls of Minerva are the clear choice. The extra policy slot and, more importantly, the Gilded Vault building which gives another trade route, are perfect for Portugal’s strategy.
- Economic Policy Control: Your government should be a Merchant Republic for the extra trade route and discount on gold buys. Your policy cards should be full of economic boosts: Wisselbanken, Triangular Trade, and E-commerce will make your gold income truly massive.
Late Game (Industrial Era and After):
- Win How You Want: With an economy that can make thousands of gold per turn, any way to win is possible.
- Science Victory: Just buy your Spaceport and all the projects. Use your gold to get Great Scientists and Engineers to speed things up. Build Oxford University and any other science-boosting wonders you can.
- Diplomatic Victory: Your huge wealth lets you win every aid request and competition. You can buy all the diplomatic favor you need from other civilizations. Building the Statue of Liberty and the Potala Palace will be easy.
- Cultural Victory: Buy every Great Work of Art, Music, and Writing. Get every Great Artist, Musician, and Writer. Build every culture wonder. The amount of tourism you can create with things you buy is huge.
Portugal in an OCC shows how money can’t be stopped. You’re not just building a city; you’re building the world’s bank, and every other civilization is just a customer.
The Maya: Mastering the Perfect Single City
While Portugal’s strength is in reaching out, Lady Six Sky’s Maya finds its power in being perfect inside. The Maya are the best “tall” civilization, with abilities that help you for putting all your power in a small, highly developed area. For the One-City Challenge, their abilities aren’t just helpful; they are a guide to making a single city with more people and science than any other.
The Mayan Plan for a Giant Capital
The main part of the Mayan OCC strategy is the leader ability, Ix Mutal Ajaw. This ability gives a 10% bonus to all income for cities within six tiles of the capital, and a -15% penalty to all income for cities outside this area. In an OCC, the penalty doesn’t matter, and the 10% bonus is a constant, strong boost to your whole economy. It also gives +1 Amenity for every luxury resource next to the City Center, so happiness is never a problem and you can have a huge population.
This is helped by the civilization’s special district, the Observatory. It replaces the Campus, is cheaper to build, and gets a +2 science bonus from every nearby plantation and a +1 from every nearby farm. A well-placed Observatory, with farms and plantations around it, can produce a huge amount of science from the early game.
Real Example: You settle your capital with three plantation resources (like Spices, Tobacco, Cotton) and three farmable bonus resources (like Wheat, Rice) close together. You put your Observatory in the middle of these. From plantations alone, that’s a +6 science bonus. Add a few farms, and you have a +8 or +9 science district before any buildings or policy cards. This is an amount of early-game science that other civilizations can only wish for.
How to Play: From Jade and Obsidian to the Stars
Where to Settle and Early Growth:
- Fresh Water and Resources: Unlike Portugal, a coastal start isn’t needed. Your main needs are fresh water for housing and a lot of farmable and plantation resources nearby. Hills are also good for production and for placing their special improvement, the Hul’che, later.
- Early Game Build Order: You should go for Scout, Slinger, Builder, and then right to your first Observatory. You want to use that big early science lead to get ahead in technology. Your first Builder should improve your luxury resources for the amenity bonus and then make farms around where you plan to put your Observatory district.
- Tech and Civic Path: Rush Writing to unlock the Observatory. Then, get technologies that unlock plantations and improve your farms, like Irrigation and Pottery. In the civics tree, go for Craftsmanship to unlock the Agoge policy for making units faster early on, and then go towards Political Philosophy to set up your government.
Mid-Game (Classical to Renaissance Era):
- The Population Growth: With the amenity bonus from Ix Mutal Ajaw, your city can get very big. Focus on building the Granary and Sewer as soon as you can. The Hanging Gardens wonder is a great choice if you can get it, as the 15% growth bonus will apply to your already growing population.
- Wonder Synergy: Kilwa Kisiwani is still a top wonder for the Maya. Your large population will be working many tiles, and Kilwa’s percentage-based income boosts will be very strong. The Oracle is another great choice, as the extra Great Person points will help you get the important Great Scientists for a science victory.
- Defensive Strength: Your special unit, the Hul’che, is a strong defensive tool. It’s stronger than the Archer it replaces and gets a combat bonus when attacking hurt units. Put a few of these in your city and on nearby hills to stop any aggressive neighbors. In an OCC, you are an easy target, and a strong defense is very important.
Late Game (Industrial Era and After):
- The Unstoppable Science Power: By the late game, your single city will have more than 30 or even 40 people. With Pingala as your governor, fully promoted, and the right policy cards (Rationalism, International Space Agency), your science production will be huge. You will probably be making more science from one city than other civilizations are from their whole empires.
- Way to Victory: Science is Key: While a Cultural victory is possible because of your large population and ability to get Great People, the Science victory is the most direct and sure way for the Maya. Your production might be less than Portugal’s buying power, but your pure scientific output will be the best.
- Using Your Production: While you can’t buy everything like Portugal, your large population gives you a good production base. Build an Industrial Zone and a Factory, and add the Ruhr Valley wonder if you can. Use your faith (from any Holy Sites or wonders) to get Great Engineers to rush the Spaceport and its projects.
Playing the Maya in an OCC is a great lesson in focused growth. You will make a single, bright example of scientific and cultural success, a city so big and advanced that it makes the rest of the world jealous, eventually going to the stars while others are still fighting over land.
Ethiopia: The Steady Power of Faith and Change
For a really different and strong One-City Challenge game, Menelik II’s Ethiopia gives a great option to the economic and scientific giants. Ethiopia’s strength is in its power to make huge amounts of Faith and then turn that Faith right into Science and Culture. In an OCC, where every bit of income is important, this ability to change is a game-changer, letting you switch and adjust in a way that many other civilizations can’t.
The Ethiopian Way: Faith as the Best Money
Ethiopia’s whole plan is based on its leader ability, Council of Ministers. This ability gives a 15% bonus to your city’s Science and Culture for every resource on a hill. It also lets you build the Rock-Hewn Church, a special improvement that gives +1 Faith and another +1 Faith for every nearby hill and mountain tile. When put in the right places, a group of Rock-Hewn Churches can make a huge amount of Faith.
This Faith isn’t just for winning with religion. The main part of the Ethiopian OCC strategy is to use this Faith as money for everything. With the Grand Master’s Chapel building in your Government Plaza, you can buy land units with Faith. With the Jesuit Education belief, you can buy Campus and Theater Square buildings with Faith. And with the right Great People, you can do almost anything.
Real Example: You settle your capital on a hill, with other hills and a mountain range around it. You put a Holy Site next to a mountain for a big bonus, and then you start putting Rock-Hewn Churches on the hills around. A single Rock-Hewn Church next to three hills and a mountain will make 5 Faith per turn. A group of four or five of these churches can easily make 20-30 Faith per turn just from improvements, plus your Holy Site income. By the mid-game, an income of 200+ Faith per turn is not just possible, but what you should expect.
How to Play: From a Mountain Church to World Power
Where to Settle and Early Faith:
- Hills Are Key: Your starting spot is very important. You must settle on a hill, and you need a city spot with a lot of hills around. Mountains are a plus for Holy Site bonuses. Not having enough hills will ruin your whole plan.
- First Moves: Your build order should be about setting up your Faith production. Scout, Builder, and then a Holy Site should be your main goals. Use your first Builder to start chopping woods to build your Holy Site and its Shrine faster.
- Starting a Religion: Getting a religion is a must. Go for the Astrology technology early. Your Pantheon belief should be one that helps your Faith, like Religious Idols (+2 Faith from Mines over luxury and bonus resources) or Dance of the Aurora if you start in the tundra. Your religion should be made to help your OCC. Jesuit Education is the best belief you can get. Work Ethic (Holy Site bonus also gives production) is also very strong.
Mid-Game (Classical to Renaissance Era):
- The Faith Boom: Once you unlock the Rock-Hewn Church with the Medieval Faires civic, your faith production will go up a lot. Use your builders to make a network of these improvements on every hill you can.
- Government and Governors: The Theocracy government is the clear choice for the mid-game, giving a discount on all Faith buys. Pingala is still a great choice for his general income boosts, but Moksha with his Divine Architect promotion (letting you buy districts with Faith) gives a very strong other way to play.
- Key Wonders: Kilwa Kisiwani is, again, a top wonder. You will have the faith and gold to be suzerain of important city-states. The Mahabodhi Temple is another great choice, giving a lot of Faith and two Apostles to help you protect your religion. The Hagia Sophia is also good for the extra spread on your religious units and the bonus faith.
Late Game (Industrial Era and After):
- Ways to Win: Science or Culture with Faith:
- Science Victory: With Jesuit Education, you can buy every building in your Campus and Spaceport districts right away. Your high Faith income lets you keep getting Great Scientists and Great Engineers. You will basically be buying your way to the stars, but with Faith instead of Gold.
- Cultural Victory: A faith-based Cultural victory is also very possible. Your Rock-Hewn Churches give a place for relics when you play with the Voidsingers secret society. You can use your Faith to buy Naturalists to make National Parks and Rock Bands to spread your culture. Building wonders like the Eiffel Tower and Christo Redentor will be much easier when you can buy the buildings you need and get engineers.
- Diplomatic Options: While not the main way, your high faith income can also be turned into diplomatic power. If you need to, you can use your faith to buy units to finish city-state quests or to defend yourself, which gets you diplomatic favor.
Playing Ethiopia in an OCC is a game of smart changes. You will turn the rough, hilly land into a source of pure faith, and then use that spiritual power for real scientific and cultural gains. It is a special and very rewarding way to win, showing that in the world of Civilization, faith can really move mountains.
The One-City Challenge is the final test of a player’s smarts and a civilization’s natural strengths. While many can try it, Portugal’s money power, the Maya’s natural fit with playing tall, and Ethiopia’s flexible faith-to-income ability are the strongest and most sure ways to win. Each gives a special and very interesting game, pushing the limits of what can be done with a single, perfect city. Master one of these civilizations, and you won’t just win the game; you will reach a level of focused skill that big empires can never dream of.