The world of OKAM will be very barren in the beginning, until players start to construct outposts; over time, the more successful outposts will turn into villages, towns, cities. All of that is fully player-controlled and designed. While outposts or small production facilities can be run alone or with a group of friends only, the larger you want to become the more feudal you have to become.
The 4 Pillars of a successful city (or: what can I do in OKAM?)There are various different roles that appeal to different players. There is no actual role classification, you can create characters that specialise in one or try and do everything.
The WorkerThe worker is the economical backbone of every well run city, ensuring that whatever the city needs, the city gets. This includes the production of raw materials (based on the location), the crafting of necessary items (tools, weapons, intermediary products) and trading with other locations to receive goods that are not commonly available in your territory. This is run independently (you, as a person, decide what to produce, usually based on the cities supply/demand) and to large parts automatically (you send your family to work, you don't stand on a field to harvest wheat). You can be specialised in something specific, with the drawback of not being able to react to changes in the economy quickly, or generic, with lower income, but higher flexibility. If your city is run well, this should be a low-danger activity. Being a merchant is medium-danger, as you will travel to other settlements, exposing yourself to the possibility of raids.
The ExplorerThe explorer has certain tools to help him find the world's hidden treasures. That can be either yields for raw resources or what is (temporarily) called blueprints. The main gameplay element is walking out into the uncontrolled lands to find those valuable spots. Think of the geologist in "settlers". Just armed.
The explorer lifestyle will be the one of the most dangerous ones, you can expect a lot of rivalry out in the open. Someone might get hurt, even. When you find someone out in the open, you can expect him to be there for the same reason you are - he is a treasure hunter. And he might have treasures on him. Or he might suspect you to have the same. I think you get where this is going.
Yields
Yields define the geographical value of a location. Some cities will have high quality wood, or high quality trees, or high quality soil.. etc. No city will ever have all it needs.
Yields will never run out. You have what you have, as long as you hold the location. This is to make sure creating long-term plans to overtake those locations is viable. There will be no "oh we just wait until they run out of iron". They will not, you will have to take it from them.
However, the technological race over yields is a very important one. In the beginning, everyone has limited tools, and the yields you can find will do, but to stay competitive you have to keep searching, keep finding better and better resources to use them yourself, or sell them at a good price to the best buyer.
Blueprints (temporary name)
Another thing hidden in the world is blueprints. (there will be an explanation for that, stay tuned) It is basically an instruction on how to build things in the world, be it weapons, armors, or buildings. Those blueprints come in different quality, and the combination of demand and quality will define their price on the market. High quality Blueprints will be extremely valuable, and sought after.
Specialised blueprint-traders are to be expected - people with good relations to different cities and their lords, and knowing who wants what.
The WarriorThe warrior comes in different variations - from a simple grunt, known for his proficiency in fights, to brilliant strategists, trusted with armies to conquer or defend areas. Having a large army by itself means nothing without having skilled players taking control of them. Warriors will split into different subcategories like soldiers, raiders, escorts, etc. Whenever you expect to have to fight, you may want some of those with you. The difficulty and risk of this playstyle can range from "smooth sailing" to "omg my family was wiped out".
The PoliticianThe most difficult and advanced playstyle, as it will require a lot of social skills. When you start turning your little lumbercamp into a full blown city, you will need to manage it well. And the higher you get, the less power you will actually have - feudalism at it's best.
You need to make sure that the people in your city are happy. What is a happy citizen? One that feels you are not screwing him over. One that feels protected. One that is rich.
Population
Who lives in a city? Well people, obviously. Players. Player families. Cities are where they are protected, where nothing bad happens to them, where they can practice whatever playstyle they want without having to look over the shoulder every second, worrying about a bandit attack or a murderer hidden under their bed. Cities have to attract players, and as a ruler it is your job to make your city as attractive as possible. Keep the area safe. Make sure that attacks towards you are dealt with swiftly, ideally without impacting your economy.
New players want to be wooed. Do you give them incentives? Like a house for free? Or a set of armor as a welcome gift? Possibly with your city colours, so they work as walking advertisements out in the city? All of that costs money. You gotta spend money to make money, right?
City Design
Each city will be split in different districts that are run by different lords. Those lords can (and will have to) split their districts again, and again, and again... If everything goes well, you will have a city that is producing steady silver that you invest into your city. Those investments attract people to live in your city, and people in your city mean power. Power to produce, power to wage war. Without people living in your city you are weak and defenceless. With many people you are on the right path to take control of the kingdom.
Currency
How do you get money as a city? You simply create it. You have people creating money. So you could send all your people into a mine to dig up silver and you will be the richest city. However, if you don't give that money back to your people, they will leave. They will go somewhere else, where they are actually benefiting from living there. Where producing goods pays off, where they can slowly advance in the horrible feudal-capitalistic society that OKAM will be. Having people loyal to your cause will help, but at a certain point you will require the help of the unwashed masses.
Taxes
Of course having people in your city has to give you something. That's taxes. But simplified. Let's cut all the complex bullshit and let's boil taxes down to what they really are: They are lifetime stolen by the government. So that's what you can do, you can steal lifetime of your population, part-time slavery if you will. The higher the "tax", the more you can allocate workers to city-relevant tasks - building defenses, drafting soldiers, creating money. If you go too low, you will not be able to run your city properly - reinvest money or defend from attacks. If you go too high, people will be annoyed and find another city that offers them a better living situation. Or, if things go really bad, they will revolt and try taking over the city from the bottom; best case is you have to wage a bloody civil war within your own city, worst case is you get driven out and lose all your power.
Armies
Armies work similarly to taxes - you draft from your population, taking away lifetime from your population. Your people will understand to some extent, but if you just abuse them as cannon fodder, possibly even without pay, they will at some point become unhappy. Waging war within your area will be relatively cheap, as you don't have far distances to travel, but the further you try to expand your power, the more difficult it will become to keep up the numbers needed for such a warfare. Better make sure you have all your cities under control.