Feudalism is a Civil Service upgrade which increases basic resource output from clicking the buttons 'Gather Food', 'Cut Wood', and 'Mine Stone'. The upgrade cost is 10,000 Piety.

Initial SkinningHarvestingProspectingMasonry
Masonry DomesticationPloughsharesIrrigation  –  ConstructionGranariesBasic WeaponryBasic Shields  –  Horseback RidingThe Wheel  –  Writing
Construction ButcheringGardeningExtraction  –  Architecture  –  TenementsPalisade
Architecture FlensingMacerating  –  Crop RotationSelective BreedingFertilisers  –  Slums  –  Civil Service  –  Start Building Wonder
Writing AdministrationCode of LawsMathematicsAesthetics
Civil Service FeudalismGuildsSerfsNationalism
Trade TradeCurrencyCommerce