Formulas
This page describes how Freeciv21 computes what happens in the game. It is intended as a reference for ruleset authors and players who want to heavily optimize their actions. Developers may occasionally find it useful, too.
Unit Bribe Cost
The amount of gold needed to bribe a unit is primarily governed by who much the
unit costs, the base_bribe_cost ruleset setting, and how far the unit is
from the nearest capital city (capped to 32 tiles). The amount of gold the
opposing player has also plays a role. The base cost is computed as follows:
Several multiplicative factors are applied on top of the base cost:
Rulesets can modify this cost through the Unit_Bribe_Cost_Pct effect:
\[f_\text{effects} = 1 + \frac{\texttt{Unit\_Bribe\_Cost\_Pct}}{100}\]Veteran units are more expensive. The cost is increased by two factors, the combat power factor \(f_\text{power}\) and the relative speed of the unit compared to a green one, \(f_\text{MP}\).
Finally, a discount is given if the unit is short on HP, reducing the cost by up to 50% if the unit has no HP. This is computed as follows:
\[f_\text{HP} = \frac{1}{2} \left( 1 + \frac{\text{unit HP}}{\text{base HP}} \right)\]
The total bribe cost is then computed as: