Resourcesare naturally occurring deposits of goods with a cultural or economic interest, as are Luxury Resources, or strategic relevance, as are Strategic Resources. Empires set up Access to a resource by constructing an Outpost in the territory where the resource is found, then building an Extractor district onto the resource.
Access to a resource is automatically shared with all the cities within the same Empire. Thanks to Trade, other Empires may also buy Access to the same resource. When doing so, Access is shared between the Empire which owns the resource and all the Empires which they are trading with. Once bought by an Empire, Access is maintained without requiring any further action or management from both parties but can be disrupted through violent actions.
Players who know the position of a Tile containing an exploited Luxury or Strategic Resource can buy the Access to this Resource if it belongs to an Empire with which they can trade. This will automatically create a Trade Route between the Territory the Resource is in and the closest City of the buyer, as long as there is a valid path available i.e., a path that goes through neutral Territories or Territories of other Empires with whom they can also trade. Otherwise, the Resource cannot be bought. Players buying a Resource this way do not need to have researched the Technology required to exploit it. Resource Access cannot be bought from a Territory whose City is under Siege or Occupied, or from an Extractor whose District is currently being Ransacked.
When setting up a Trade Route, buyers can choose between different means of transportation to prioritize: land, sea (once they have built a Harbor ) or air (once they have built an Airport ). Depending on which option is selected when buying Access to a given resource, the resulting Trade Route will minimize the use of all but the preferred means of freight. Trading by land is the most accessible choice but is very prone to disruptions through violent or political means. Trading by sea is often a safer and cheaper choice, as long as you stay close to the coast. Trading by air is initially the most expensive, but the Resource passes through fewer Territories that way, compensating for its high price. It is also the safest way to transport what you need.
When a Trade Route passes through a neutral Territory, a neutral Trading Post is created there and stays there until someone settles in the Territory. It can be Ransacked as if it were an Outpost belonging to an Empire that players are at War with, rewarding the attacker with a lot of Money. When this happens, the Trading Post and all the Trade Routes that pass through it are instantly destroyed. However, a Trading Post will continue to exist, even after all its Trade Routes have stopped passing through it, as future Trade Routes passing through it will be cheaper to set up.
When trading by sea, there might be situations where there is no Harbor in a Territory you want your boats to transfer their cargo to. In this case, a Trade Port will be created in exchange for a slightly higher trading cost. Trade Ports are Trade Route waypoints that enable a land-based resource to be shipped overseas. Like Trading Posts, they can be ransacked for Money, destroying it and the Trade Route passing through it. Trade Ports disappear once a Harbor is built in their Territory (Note: if a Trade Port exists, the cost of building a Harbor is lower).
The cost of a Resource depends on multiple factors. The most important are the following:
The total amount is directly given to the owner of the Resource being bought. Note that there are also bonuses that will increase or decrease the cost of a Resource independently of the base computation.
Once a Trade Route is established, Empires along its path may also receive passive income depending on their Districts, Civicsor Traits.
Trade Routes do not expire naturally, and they will last until they are destroyed. This can happen either by changes in the diplomatic relationship between the Trade Route’s creator and an Empire along its path because either the original Extractor, one of the Trade Posts, Trade Ports or an Administrative Center along its path has been destroyed due to Ransack or Bombardment, or because a Territory along the path has changed hands and the new owner's Diplomacy does not allow trade with the Trade Route’s creator.
A Trade Route can also be temporarily frozen if its path is no longer valid, but not yet destroyed. This could happen when an Empire whose Territories the Trade Route goes through makes a Demand on the Trade Route’s creator, when the City from which the Resource comes from is under Siege, or the Extractor is being Ransacked.