Games like Starfold
Games like Starfold include Prison Architect, Kingdoms and Castles, Cities: Skylines, Manor Lords, and Timberborn. We matched them by the tags players give Starfold on Steam (City Builder, Colony Sim, Strategy, Sandbox, and Space): closest matches first, and among equally close ones the better-known games.

Prison Architect
Shared: Sandbox · Colony Sim · Building

Kingdoms and Castles
Shared: City Builder · Colony Sim · Strategy

Cities: Skylines
Shared: City Builder · Strategy · Building

Manor Lords
Shared: City Builder · Strategy · Simulation

Timberborn
Shared: City Builder · Colony Sim · Sandbox

Banished
Shared: City Builder · Colony Sim · Strategy

Cities: Skylines II
Shared: City Builder · Sandbox · Building

Foundation
Shared: City Builder · Strategy · Sandbox

Dwarf Fortress
Shared: Colony Sim · City Builder · Strategy

RimWorld
Shared: Colony Sim · Strategy · Sandbox

Against the Storm
Shared: City Builder · Strategy · Simulation

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

Workers & Resources: Soviet Republic
Shared: City Builder · Strategy · Simulation

Empires of the Undergrowth
Shared: Strategy · City Builder · Colony Sim

Dyson Sphere Program
Shared: Space · Building · City Builder

Ostriv
Shared: City Builder · Strategy · Colony Sim

Space Haven
Shared: Colony Sim · Strategy · Space

Norland
Shared: City Builder · Strategy · Colony Sim

The Universim
Shared: City Builder · Colony Sim · Sandbox

Settlement Survival
Shared: City Builder · Colony Sim · Building

Frostpunk
Shared: City Builder · Strategy · Colony Sim

Going Medieval
Shared: Colony Sim · Strategy · City Builder

IXION
Shared: City Builder · Strategy · Space

Planet Coaster
Shared: Sandbox · Building · Simulation