Sins of a Solar Empire: Rebellion – How Culture Works


This guide attempts to explain the (as accurately as can be determined experimentally in-game) workings of culture. Keep in mind that most of this information has very little practical applications and impact on a game. Most of the time, all you really need at all is “culture spreads slower the farther it travels”. This guide is intended for those who already know what culture even is and what it affects, and want to know precise numbers and have a deeper understanding of culture.

Also note: This information was derived from plenty of testing and observations in-game and could very well be very wrong.

Culture Spread

First and foremost, how much culture does a single Broadcast Center / Temple of Communion / Media Hub produce? Better yet, what does it mean to “produce culture”?

Producing culture at a planet is to fill connecting phase lanes with the color of your empire. The speed at which they fill is proportional to how much culture is “flowing” down that lane. The total culture production of a planet is the sum of the culture produced by all the cultural structures on that planet. Simple so far. At this point it would make sense to give the production and flow of culture some kind of unit. We’ll call it C. It would also make sense to say that one cultural structure produces 1 C, but for reasons that will come later (see Culture Repellants) it is much better to define the production of 1 structure as 2 C.

Now the first important observation is that the culture that flows down each phase lane of a planet is not necessarily equal to the culture produced by that planet. Instead, the culture produced is SPLIT evenly accross each phase lane. InfoCards for planets producing culture even already reflect this under Culutre Rate, describing how much culture is flowing down each of its lanes, not the total culture produced. (side note: Culture Rate on planet InfoCards show 10 times the C). As an example, if a planet where you built 2 cultural structures has 3 connecting phase lanes, there will be 4/3 C flowing down each lane, while the planet then shows a Culture Rate of 13.3. If there was only 1 lane, then the full 4 C flows down that lane, filling it much faster, and the planet shows a Culture Rate of 40.

When the flow of culture reaches the neighboring planet, it continues to flow down the next lane or lanes of that planet. To do so, culture is first cut in HALF, and then the culture is also SPLIT evenly accross each phase lane that it continues on through. Example: The previous flow of 4/3 C reaches a planet with another 3 connecting phase lanes, one of which is the lane it arrived on. Here it is halved to 2/3 C, and then split in two again for its two lanes it continues through, resulting in a flow of 1/3 C down each.

Another important observation is that for a little more complicated phase lane networks, the culture that propagates down a planet is equal to the sum of the resulting flows for each possible path it could take to get there, without revisiting a previous planet. The simplest example would be a triangle of planets where one of them has an additional lane outwards. Building 1 cullure structure on one of the other two planets yields 1 C down each lane. There are two paths it can take to reach the planet leading outwards. Through one path it results in a flow of 1/4, through the other 1/8. The total flow out is then 3/8.

When there are multiple planets producing culture, the resulting flow propagating out of some other planet is the sum of the resulting flows for each culture-producing planet individually.


Now that we understand the details of culture spread, what does culture even do? Short answer: allegiance.

Each planet you colonize has a base allegiance percentage. This percentage begins with 100% for your capital planet, and each other planet has a bit lower percentage depending on its distance to your capital planet. For each distance, the base allegiances are as follows:

  • 0: 100%
  • 1: 90%
  • 2: 80%
  • 3: 70%
  • 4: 55%
  • 5: 40%
  • 6: 35%
  • 7: 30%
  • 8+: 25%

What allegiance does is reduce tax and extractor income of that planet down to its allegiance percentage. A planet 4 jumps away from your home planet is producing 55% of the tax and extractor income that it otherwise should.

Is there a way to improve this? Of course there is. Through culture, the allegiance of a planet can be increased by up to 10% above its base value. The rate at which it increases can be seen on the infocard when hovering over allegiance with a planet selected. This rate can reach up to a maximum of 0.07%.

To determine the rate of allegiance change of a planet, the filled color of the phase lanes come into play. 0.07% corresponds to when ALL of the connecting phase lanes of a planet are COMPLETELY filled with your culture. If not, you take the fraction that each of the lanes is filled, average them, and multiply the result to 0.07%. Example: on a planet with 3 connecting lanes, one is completely filled with your color and the other two are half full. Averaging these fractions results in (1+0.5+0.5)/3 = 2/3. The rate of allegiance change of the planet is then 0.07*2/3 = 0.0466%.

When there is enemy culture on a lane towards one of your planets, allegiance will instead begin to decrease until it reaches 0. When it does, you lose control of the planet and become unable to recolonize it until you get rid of the enemy culture. The rate at which allegiance decreases in this case is determined the same way as before, only negative. If there is enemy culture on one or more lanes as well as your own on others, both allegiance change rates are added. Example: on a planet with 3 connecting lanes, two are completely filled with your color and the other is full of enemy culture. For your culture, the resulting allegiance change rate is 0.07*2/3 = 0.0466%, and for the enemy’s culture it is -0.07/3 = -0.0233%. In total, the planet’s allegiance change rate is then +0.0233%.

When a planet has an allegiance that is not equal to its base value, and is not being affected by culture (whether because the capital moved or it was previously being affected by culture), its allegiance will move towards its base value at a rate of 0.035%, whether it is up or down.

Culture Repellants

Remember when we defined our culture unit C? Why define the culture of one Broadcast Center / Temple of Communion / Media Hub as 2 C and not 1 C?

This is because of culture repellants. Capital Ships have a property, visible in-game on their infocard, where they prevent enemy culture from flowing toward the planet they are stationed on. They have a culture repel statistic of 0.3 at level one, increasing by 0.05 each level, up to 0.75 at level 10. However, this statistic is halved when station on neutral planets, and reduced to 0 on enemy territory. Because they are given a concrete value we can base our unit C on that. Experimentally it shows that culture structures produce not 1 but 2 C.

Planets with neutral minor factions on them also repel all non-allied culture flowing towards them at 1.5 C. To spread your culture past them, you need either at least 1.5 C or make them your allies.

Unlike normal culture, culture repel does not flow down lanes and is not split evenly across each lane. It only hinders culture from flowing towards it. When a culture flow towards a planet is being repelled but is still greater than the repellant, the flow is reduced by the repellant’s amount but continues flowing. If the repellant is equal or greater, the flow is stopped completely and decays as though there was no culture at all.

The big important thing to note about repelling culture is that each single, isolated flow of culture is repelled individually. This includes the previous rule where the total flow is the sum of flows of all possible paths. The only exception is when there are multiple culture producing structures on the same planet, where they are indeed added together and repelled as one flow.

What this means is that in order to completely stop a flow of culture, only enough repel to stop the largest of its components is necessary. In the much earlier example of culture flow in a triangle of planets with one leading out, a culture repel of 0 to 1/8 C linearly reduces the outgoing flow from 3/8 down to 1/8 C (essentially twice as strong repel), and between 1/8 and 1/4 C repel reduces the flow linearly between 1/8 down to 0. To reiterate, only a culture repel of 1/4 C is needed to stop the flow completely, not 3/8 C.

Encountering Enemy Culture

Basically, when your flow encounters an enemy flow in the opposite direction, the larger of the two keeps flowing, at a speed as though it was reduced by the magnitude of the other’s culture. (It is not ACTUALLY reduced).

When your flow and an enemy flow meet at a planet, the winner keeps flowing as normal, that is to say it is halved and split by (total number of lanes – 1), and in addition reduced by a factor of (winner culture / sum of all cultures). For example your culture of 2 C meets an enemy culture of 1 C at a 4-way intersection, your resulting flow out each lane is

2 * (1/2) * (1/3) * (2/3) = 2/9 C.

Since 2/9 is not greater than the enemy’s culture of 1 C, the enemy’s culture stays put and yours flows out the other 2 lanes at 2/9 C.
If instead of 2 C you had 7 C, your flow out each lane is (initially)

7 * (1/2) * (1/3) * (7/8) = 49/48 C = roughly 1.021 C.

Since this is greater than 1 C, the enemy’s culture is pushed back, meaning that cultures are no longer meeting at a planet, meaning that your culture is no longer reduced due to that, so now your flow out each of the other 3 lanes is actually

7 * (1/2) * (1/3) = 7/6 C.

Helena Stamatina
About Helena Stamatina 2990 Articles
I love two things in life, games and sports. Although sports were my earliest interest, it was video games that got me completely addicted (in a good way). My first game was Crash Bandicoot (PS1) from the legendary studio Naughty Dog back in 1996. I turned my passion for gaming into a job back in 2019 when I transformed my geek blog (Re-actor) into the gaming website it is today.

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