From Alpha Centauri Wiki
- Difficulty Level: at the easiest difficulty level, every citizen after the first six is a drone. For each increase in difficulty level, the number of citizens before drones appear due to a base's population decreases by one, so at the most difficult level every citizen after the first begins as a drone.
- Bureaucracy: Depending on Efficiency and Difficulty level, additional drones are received when the number of bases exceeds a certain number.
- Disloyal Citizenry: For approximately 50 turns after a base is captured, it will receive extra drones while it is assimilated. The basic rate is five drones minus one for each 10 turns elapsed, but the number may never exceed: (BaseSize + Difficulty - 2) ÷ 4 .
- Faction Power: Some factions receive additional drones or talents. For instance, the University of Planet receive an extra drone for every four citizens (rounded down), while the Peacekeeping Forces receive an extra Talent for every four citizens, rounded up.
- Pacifism: If social engineering Police rating for a base is at -3 or less, Drones will be created for each supported military unit away from territory and for each non-air superiority aircraft. These drones may not be pacified through the use of Psych, nor drone-reducing facilities (excluding a Punishment Sphere). Only Talents, or a secret project may prevent a drone riot caused by pacifism.