Games like First Feudal
Games like First Feudal include Oxygen Not Included, Prison Architect, Kingdoms and Castles, Frostpunk, and Manor Lords. We matched them by the tags players give First Feudal on Steam (Colony Sim, Base Building, Resource Management, Building, and Simulation): closest matches first, and among equally close ones the better-known games.

Oxygen Not Included
Shared: Colony Sim · Base Building · Resource Management

Prison Architect
Shared: Base Building · Building · Colony Sim

Kingdoms and Castles
Shared: Colony Sim · Resource Management · Simulation

Frostpunk
Shared: Resource Management · Colony Sim · City Builder

Manor Lords
Shared: Base Building · Simulation · Strategy

RimWorld
Shared: Colony Sim · Base Building · Strategy

Against the Storm
Shared: Base Building · Simulation · Building

Dwarf Fortress
Shared: Colony Sim · Base Building · Simulation

Banished
Shared: Colony Sim · Simulation · City Builder

Foundation
Shared: Simulation · Medieval · Resource Management

Factorio
Shared: Base Building · Resource Management · Crafting

Farthest Frontier
Shared: Building · Resource Management · Colony Sim

Empires of the Undergrowth
Shared: Base Building · Simulation · Colony Sim

Norland
Shared: Base Building · Colony Sim · Simulation

Settlement Survival
Shared: Colony Sim · Building · Simulation

Life is Feudal: Forest Village
Shared: Colony Sim · Resource Management · Simulation

Workers & Resources: Soviet Republic
Shared: Base Building · Simulation · Strategy

Ostriv
Shared: Colony Sim · Simulation · Base Building

Space Haven
Shared: Colony Sim · Base Building · Simulation

Cities: Skylines
Shared: Building · Simulation · City Builder

Tavern Master
Shared: Building · Simulation · Resource Management

Planetbase
Shared: Colony Sim · Base Building · Resource Management

Endzone - A World Apart
Shared: Base Building · Colony Sim · Simulation

Blacksmith Master
Shared: Base Building · Colony Sim · Simulation