Since Planetfall's release there have been numerous releases and updates to the game that have outdated many current Steam guides, YouTube videos, and even the wiki for Planetfall. This guide will be the complete and current guide to Sectors and Exploitations, updated as of June 2021. Significant developments to Planetfall are very unlikely as the game is effectively finished, hopefully making this guide evergreen. Note this is not a strategy guide, this is simply an explanation of the mechanics behind acquisition and Exploitation of Sectors.
All races function the same for the purposes of the guide below. The principles behind Sector annexation and Exploitation are identical across all factions.

All maps are divided into distinct, bordered areas called "Sectors". There are 2 kinds of Sectors: Water Sectors and Land Sectors. All sectors have a "center" hexagon. This is not its geometric center necessarily but it is the tile where Exploitations, your Colony, and Landmarks must reside. This is also the hex you click on for more information about the Sector (this opens the Sector Analysis window).

Land Sectors have both a Climate and a Terrain. This is what determines the possible Resources that are exploitable. There are 4 different Resources: Energy, Knowledge, Production, and Food. The different Climate and Terrain each provide two of the four possible Resources. For example an Arid Climate provides 1 Energy and 1 Production. Combined with a Fertile Plain Terrain which provides 1 Food and 1 Knowledge, would in total provide 1 of each Resource. There are four "standard" Climates and four standard Terrains for Land Sectors.
Ignoring the above, what this means is each sector has a combination of 4 Resources. It can have 1 of each , 2 of one resource and 1 of two others , or a pair of two resources (due to Climate and Terrain never having 2 of the same Resource you will never see 3 or 4 of one Resource on a Sector).
Other than Terrain and Climate, Land Sectors often have other elements such as Resource Nodes, Features, Hazards, and Landmarks. These will be discussed later.
Note some Sectors are not habitable and cannot be annexed or colonized. These are quite obvious as they contain no Resources.

There are two exceptions to the above rule. Some Land Sectors are known as "Wilderness" and are nothing but mountains. They are not colonizable and cannot be annexed. They have to be terraformed first which only the Dvar can do with the appropriate technology. A second type of Land Sector has "Volcanic" Climate. Volcanic Climate produces no resources at all, and these Sectors only have Resources from the corresponding Terrain. In fact if annexed or colonized will generate -8 Happiness, making them the worst Climate types.



Above is a Land Sector that has not been claimed by anyone. Because it is Arid it generates a and a . And, because it is a Mountain it also contains a and a , leading to a final Resource distribution of . It also contains a blue triangle (corresponding to an Ion Storm hazard) and a blue diamond (corresponding to a Cosmite Resource Node). Its name is the "Abyssinian Crucible", which has no gameplay functionality.

When your Colony grows to a multiple of 4, you are allowed to annex another Sector. A new Sector is therefore gained at 4/8/12/16 population. The Sector you want to annex must be adjacent to either your Colony or another annexed Sector and must not be more than two Sectors from the Sector containing your Colony.
Simply click the center hex of a neighboring territory and click Annex to bring the territory under your control. Annexing costs no Resources but does take one turn.
At a population of 16 you can annex a maximum of 4 sectors. Normally 4 annexed Sectors is the maximum number even with a higher population. Residential Exploitations can increase the number of annexations. These are discussed in a later section. Note the Colony screen will show 5/5 Sectors instead of 4/4 annexed Sectors, but that is because they are including your Colony Sector which is not technically annexed.
The newly acquired territory will have a "Sector Base" garrison at the center hex and a new road connection to any neighbouring Sectors. However, you gain no extra resource income by simply annexing territory (Resource Nodes are the exception, see the Resource Nodes section). In order to start getting income from the sector an Exploitation must be built.

This is an annexed Sector belonging to a nearby Colony. The Colony gains no Resources from this Sector as it does not have an Exploitation. Exploited Sectors have a corresponding Resource icon in the center hex showing the Exploitation. In this case, the Sector's center hex is empty (note this is empty only in the Economic Overview, the Military Overview shows a yellow flag signifying the center hex contains a Sector Base). Moreover, because it contains no other features, particularly Resource Nodes, this Sector requires an Exploitation to generate any Resources at all.

Once annexed, a Sector can then be exploited. These Exploitations are built through the Sector Production tab in a Colony. The structure is constructed at the center of the Sector. Only one of the Resources can be extracted from the Sector, even if the Sector has all 4 resource types. The other Resources are simply not used. You can even exploit a Resource that is not on the Sector at all! This is not advisable since the gain per turn will be quite small.


The amount of income you generate per turn from an exploit is determined by the 4 resources on that sector which as explained above is determined by the Climate and Terrain. Let's take Energy for example:
If there are 0 Energy icons on a Sector and you build the Energy Exploitation anyway, you get 10 Energy per turn. This is a Level 1 Exploitation, the lowest/worst.
If there is 1 Energy icon on a Sector and you build the Energy Exploitation you get 15 Energy per turn. This is a Level 2 Exploitation.
If there are 2 Energy icons on a Sector and you build the Energy Exploitation, you get 20 Energy per turn (which is the case in the above example). This is a Level 3 Exploitation.

Once an Exploitation is built, it occupies the center hex of that Sector, and a Roman numeral signifies the level of the Exploitation.
You may notice that there are 5 possible levels of Exploitation. How is this possible if there can't be more than 2 Resources on a Sector? The answer is by Researching and then building Sector Upgrades in your Colony (see the section below).

Another important consideration is that a Colony can only support 2 of a single Exploitation. For example, a Colony with 2 Energy Exploitations can no longer build other Energy Exploitations.

Once an Exploitation has been built, more advanced structures known as Sector Specialization Structures can be built (see the section below).

There are 3 other Exploitations which are discussed in later sections: Hydro-Exploitations for Coastal Sectors, Residential Exploitations, and Orbital Relay Exploitations.

At tier II, the "Resource" Development I research becomes available for each of the four primary Resources.
This is the Imperial Archives entry for Food Development. On the right you can see it has unlocked the Colony Building "Food Sectors Upgrade", this is built like any other Colony building. Below this are two buildings: Bioengineered Food Plantation & Agricultural Export Center. These structures are known as Sector Specialization Structures.
Knowledge, Energy, and Production Development follow an identical pattern for their research entries.

Food/Production/Knowledge/Food Sectors Upgrade I & II are structures built at the Colony building tab. They raise the level of all Exploitations of that Resource type for all Sectors belonging to that Colony.
For example, you have a Sector with 2 Energy Resources on it. You then build an Energy Exploitation and because you have 2 Energy Resources, it becomes a Level 3 Exploit which collects 20 Energy per turn. By building an Energy Sectors Upgrade in the Colony it then upgrades to a Level 4 Exploit generating 25 Energy per turn. Any other Energy Exploited Sectors also go up a level as well. To reach the highest level, level 5, the tier VI Resource Development II technology has to be researched and the corresponding Sectors Upgrade II built in the colony.
You will find these new Sector upgrades In the Structure Production tab. The game usually tells you how many Sectors will benefit from building the upgrade. Note you can actually have a Level 5 Exploitation (usually through a Landmark) and still able to build a Sector Upgrade, but the game will tell you that is provides no benefit.
After you've built an Exploitation for a specific Sector, you are then allowed to build Specialization buildings. There are 3 buildings per Exploit type. The first two are researched with Resource Development I at tier II research, and the third Specialization is researched with the tier VI Resource Development II. You are only allowed to build one of the possible three buildings per Exploitation. But because you can exploit two Resources per Colony, you can have two out of the three possible Specialization buildings. These structures provide unique discounts with either a Military or Civil focus. Note in the picture below they benefit from higher Exploitation levels.


These are the two possible Specializations for an Energy Exploitation. The third Specialization is available at the tier VI research. Note the Energy Exploitation had to be built first before you can pick Specialization Structure you want. You do not however need to build the corresponding Resource Sectors Upgrade however.

The full sequence for maximum Exploitation gain is therefore: Choose which Sector to Annex, Choose which Exploitation to build on that Sector, Choose which Sector Specialization Structure for that Exploitation, and finally build the Resource Sectors Upgrade to increase the Exploitation level.

Land Sectors can be colonized by moving a Colony Unit to the central hex. It can only be colonized if it's not occupied by a Landmark, an NPC or AI city, and it's not adjacent to another Colony. While you will get the resources per turn from Resource Nodes, you do not have an opportunity to Exploit the resources from Climate and Terrain. This makes 1/1/1/1 Sectors a good choice for colonizing since they are the worst for exploiting.

Despite not being able to build an Exploitation at the Colony Sector, the Colony itself always generates a fixed amount of resources. This income is regardless of Terrain type and is always 60 Production, 20 Food, and 10 Happiness. Note the HQ Colony, your starting one, gets additional income on top of the above Resources.

The majority of the resources you gain per turn will be done passively through building Exploitations. However, your colonies also have Colonists which can be assigned to specific resources (in addition to working "Happiness" and later the Colony District Buildings). The number of Colonists is equivalent to the population number on the Colony.
Initially when building a Colony, a maximum of 4 Colonists can be assigned to a given resource. Building Exploitations can increase how many Colonists can work a resource. Let's take Energy for example:
If there are 0 Energy icons on a Sector and you build the exploitation anyway, you can have 1 more Colonist work Energy.
If there is 1 Energy icon on a Sector and you build the Energy exploitation you can have 2 more Colonists work Energy.
If there are 2 Energy icons on a Sector and you build the Energy exploitation, you can have 3 more Colonists work Energy.

Level 4 and 5 Exploitations provide 4 and 5 extra Colonist slots respectively.



In the above picture the small Colonist icon below each level indicate how many extra slots are made available by building the Exploitation.

Colonists assigned to a slot generate 5 of that resource per turn. This can be increased by developing a Residential Exploitation (see the section below), Sector Specialization Buildings, Landmarks, and even Doctrines. Idle Colonists produce nothing and should always be slotted.

Residential Exploitations are unique Exploitations. They are built in a similar fashion as Resource Exploitations at the Sector Production interface, and their only restriction is they can't be built on a Mountain terrain. They are not affected by the Resource distribution (as defined by Terrain and Climate) on the Sector.
Residential Exploitations do 4 things:

1. Increase the productivity of each Colonist by +1, +2, or +3 with Exploitation Level 1, 2, and 3. Instead of a Colonist making 5 Energy per turn, they now generate 6/7/8 a turn. With two Residential Sectors, the income increases to +2, +4, and +6. Therefore, two Level 3 Residential Sectors increase the productivity of your Colonists from 5/turn to 11/turn.
   
2. Allow you to Annex another Sector over the usual limit. Instead of being limited to annexing 4 territories, you can now annex 6. This effectively makes Residential Exploitations "free" Exploitations in the sense they don't count against your total.
   
3. Allow you to annex Sectors adjacent to your Residential Exploitation even if they are 3 Sectors away from your main Colony Sector.
   
4. Increase the level of the each race specific Colony District Building. All Colonies can build the Basic building. The Fine building is available after building 1 Residential Sector, and the the Immaculate building is available after building 2 Residential Sectors.

Because there is no "Residential Resource", the maximum level is 3, which is increased by building the Residential Sectors Upgrade (just like other Resources) in the Colony. There are no Residential Sector Specialization Structures.

Strategically Residential Sectors should be built at either population 12 or 16. Because they do not collect flat resources per turn, their only benefit is the extra gains from your Colonists. For example, a Residential Sector built at a population of 4 is only going to provide 4 extra Resources per turn from your active Colonists, whereas a Level 3 Resource Exploit would give you 20 Resources per turn. You want a larger population to benefit from the +1/+2/+3 gain before you start constructing Residential Exploitations. The ideal Sectors for Residential Exploitations are the 1/1/1/1 Sectors, or double resource Sectors that you can't exploit further because you already have 2 of that exploit type. They can also be built to gain access to another important Sector that's 3 Sectors away (ie. a Landmark).

Orbital Relays are unlocked by researching the tier IV Orbital Relay Development technology. They are primarily built to teleport units across the map quickly.

They do provide some bonuses to your Colony. The Exploitation provides one extra Colonist slot to all Resources. Orbital Relay Exploitation have no other levels as there is this is no "Orbital Relay Sectors Upgrade" like there is for other Exploitations. This is a very poor Exploitation from an economic standpoint.



There are four Orbital Relay Sector Specialization Structures instead of three like for most Resources. Two are unlocked at the initial tier IV tech, and the final two at the tier VII tech. Only one of these has an economic benefit (shown below).



The Logistics Base Sector Structure generates at most 30 extra Resources depending on the Sectors' Exploitations. Note Hydro-Exploitations & Residential Exploitations do not benefit from Logistics Bases at all. Taken altogether Orbital Relays should be built because you need the increase military mobility rather than for the unremarkable economic gain.

There are 2 types of Water Sectors: Coastal Sectors and Ocean Sectors. Ocean Sectors are similar to the uninhabitable mountains of the Land Sectors; they cannot be colonized or annexed and are essentially useless except as areas your armies can move over.
Coastal Sectors are exploitable but cannot be colonized. Unlike Land Sectors they do not have Terrain or Climate and are all identical from a Resources standpoint. They can contain Landmarks and Resource Nodes.

Coastal Sectors cannot be annexed at the beginning of the game, but require the tier I technology below.



Coastal Sectors always have 1 Energy, 1 Food, and 1 Knowledge. However, you do not build Energy, Food, or Knowledge Exploitations like you do for Land Sectors. Instead, the only exploitation you can build on Water Sectors are Hydro-Exploitations. Never annex more than 2 water Sectors, as the only available exploitation on Coastal Sectors are Hydro-Exploitations, and you can only have two Exploitation types per Colony.

Hydro-Exploitations always start at Level 1, but you collect 10 of each resource: Food, Energy, and Knowledge. Note you gain no Production Resource from Coastal Sectors. In addition they provide one extra Colonist slot for each of the 3 resources.
At Level 2 you will collect 13 of each Resource, and at Level 3 you collect 16 of each (& 2 extra Colonist slots). There is no Level 4 or 5 as there is no "Water" resource to increase the Level beyond 3. Compared to land exploits, the total income generated from a Water Sector is 30, 39, and 48. vs Level 3, 4 and 5 Land Sectors which produce 20, 25, and 30.
Coastal Exploitations also have four Sector Specialization Structures instead of the usual three. These are quite powerful and enhance the production of the other four Resources.


In the above picture I have built a Water Exploitation on the Sector. This Exploitation is Level 2 because I built a Water Sectors Upgrade I building in my Colony. I am collecting 13 of each Resource. The "Deep Sea Mining" Resource Node is the brown cogwheel icon, which I am currently not collecting because it is still actively guarded. The "Harbor" indicates this is the Coastal region where naval military units will be created when built at the Colony. The only way to construct naval units at all is to have at least one Coastal Sector annexed. You may notice the "Sunken District" feature. For no reason, there are two Coastal features that do not show up on the game terrain as either a diamond (like Rivers or Lava) or a structure on the map. The only way to tell if a Coastal Sector has extra features is to click on the center hex and read the information. The other "hidden" feature is a Reef which provides bonus food.

Resource Nodes are the diamonds with a picture of a resource on them scattered about the map. There can be two, one, or none in a Sector. Unlike the 4 Resources from Terrain and Climate, these are claimed immediately after annexation. They do not require an exploitation to gain the income. Some do require a particular research (River and Lava River nodes for example). Others will provide an extra 5 of a particular Resource if you build a corresponding Exploitation, but they still provide at least some Resources regardless of Exploitation. Moreover the Sector that contains your Colony center will also collect these resources per turn.


Many Resource Nodes are guarded and must be cleared before their resources are made available. Guarded nodes are designated by a red border and the presence of an army. These nodes can often contain Resources that are hard to collect otherwise, such as Happiness, Cosmite, or Influence. Resource Nodes are highly desirable. They cost nothing to utilize other than clearing any guarding creatures, and are a major consideration when choosing a Sector to annex.

River and Lava diamonds are technically not listed as Resource Nodes but "features". Practically they serve the same purpose. However instead of being guarded, their benefits have to be unlocked by researching the required technology. The icons do not show up on the Economic Map until the research has been done, but the features are still present in the Sector information window.

Hazards are essentially the opposite of Resource Nodes. Your Colony incurs a penalty for annexing them, and they often cause negative effects on armies in their location.
Hazards can be permanently removed once the tier II technology Adaptive Conditioning is researched. Move any unit onto the hazard, and for 100 Energy and 15 Cosmite the Hazard will be removed the following turn.

Landmarks are structures that occupy the Center hex of a Sector. As such you can never Colonize a Sector that has a Landmark, they must be annexed. Unlike Resource Nodes the Sector cannot be annexed until the Landmark is cleared of its guards.
Landmarks are essentially prebuilt "Super" Exploitations to one of the 4 main Resources: Energy, Knowledge, Food, or Production. When annexed the corresponding Exploitation is already built and cannot be changed (but you can still pick a Sector Specialization Structure). If you already have two of the same Exploitations as the Landmark you will be unable to annex it.

Landmarks come in three tiers: Bronze, Silver, or Gold. This not only signifies the strength of the defenders, but the level of the Exploitation when annexed. Landmarks increase the level of Exploitation beyond what a standard Exploitation could. Bronze Landmarks provide +1, Silver +2, and Gold +3 levels to your Exploitation. A Gold Landmark on a Sector with none of its corresponding Resources will still start as a Level 4 Exploitation!
Note while a Gold Landmark on a double Resource Sector with 2 levels of Resource Sectors Upgrades would be at level 8 Exploitation, the maximum level is 5.
Lastly, Landmarks have other non-economic benefits. They often allow you to build powerful structures that uniquely boost produced military units from that Colony. These are built in the Sector Tab and can be built in addition to Sector Specialization Structures. Some even unlock new Strategic Doctrines or Operations.



Above is the most powerful Landmark, a Gold one. Despite this territory only having 1 Energy Resource (not shown on the screenshot), the Landmark is at level 5 (no Energy Sectors Upgrades have been built at the home Colony either). In addition to the 35 income it makes as a Level 5 Exploitation, it gives an additional 60 and 30 income. It also increases the Colonists slots over and above a Level 5 Exploitation.
But wait! There's more. It also unlocks a building in the Colony called the "Cryo-Medical Facility" (partially obscured in the picture) which boosts the resistances of any military unit produced there, and unlocks a Strategic Operation that will instantly give 3 population in a Colony of your choosing.

Landmarks are incredibly powerful structures.

The above guide is solely meant to be an explanation of how Sectors, Exploitation, and Resource accumulation occurs. I have also avoided discussing much strategy as that becomes far more contentious than simple factual mechanics.
I hope this becomes a one-stop guide that fully explains the current Exploitation mechanic, as so many guides are out of date or missing information that has been added since release. Please leave comments for issues and feedback.