Mission chance of success depends on either Happiness or Familiarity. Local Happiness is basically how much the village likes you. Familiarity is how much you know about the village. Familiarity can only ever go up, while Happiness often goes down.
First contact missions work differently. See this page:
- Main article: Native Civilization/First Contact
The formula works as follows. Let's take the False Flag Operation. To get the success chance of that mission you have to halve the village's familiarity score, so in the table it says the chance is based on Familiarity, and the formula is x0.5.
Some missions have a minimum and or maximum success chance. They are still based on the formula in the table, but if the formula causes the success chance to exceed the maximum or minimum, you take the maximum or minimum instead.
Some missions will only appear if you have over or under a specific Happiness or Familiarity score. I'm still working on figuring the exact numbers out, but I've put the data I do have in the table under Prerequisite for Availability.
It seems the game ignores Happiness penalty from Health when calculating whether missions are available, but not when calculating mission success chances. This means that for example The Shield will still be available if your base Happiness is over 75, even if that Happiness score is reduced to next to nothing because of a high Happiness penalty from Health.
After making first contact with a village, you have a Familiarity score of at least 5% with them. That's why the minimum score for a lot of missions is 5, half of 5, or double of 5. If you can find a way to decrease familiarity score you might be able to get lower than that.
Sometimes the formulas are 1% off. This is because it then rounds up or down differently.
|Mission||Based on||Times||Minimum||Maximum||Prerequisite for Availability|
|A Knife in the Dark||Familiarity||x0.5||2||(? 38-50)||?|
|A Longer Table||Happiness||x1||0||90||-|
|Bio-Weapon||Familiarity||x1||75||100||Village doesn't suffer from Plague yet|
|Bombardment||Happiness||x1||25||100||Infrastructure Level is not Stone Age|
|Death on the Wind||Familiarity||x1||75||100||Village doesn't suffer from Plague yet|
|False Flag Operation||Familiarity||x0.5||2||50||-|
|It Belongs in a Museum||Familiarity||x1||5||90||-|
|Ivory Towers||Familiarity||x1||5||80||Happiness over 25|
|Peace in our Time||Happiness||x1||0||100||-|
|Sabotage||Familiarity||x0.5||(? <5)||50||The Shield|
|The Cure||Happiness||x2 + 10||10||90||Village suffers from Plague|
|The Grand Tour||Happiness||x2||0||100||-|
|The Pen is Mightier||Familiarity||x2||10||90||-|
|The Shield||-||-||90||90||Hab Dome researched. Happiness over 75.|
|Things Fall Apart||?||?||?||100||Peace Treaty|
|Trade Treaty||Happiness||x1||(? <59)||90||Happiness over (? 55-60)|
|Trail of Tears||Happiness||x1||0||50||-|
|Uplift||Happiness||x1||(? <33)||90||Infrastructure Level is not Industrial.
Happiness over 30 (?)
|Word from on High||Familiarity||x0.5||2||50||-|