Games like Poly Kingdom: Siege
Games like Poly Kingdom: Siege include Mount & Blade II: Bannerlord, Crusader Kings III, Stronghold: Definitive Edition, Stronghold Crusader: Definitive Edition, and RimWorld. We matched them by the tags players give Poly Kingdom: Siege on Steam (Real Time Tactics, Medieval, Base Building, Colony Sim, and RTS): closest matches first, and among equally close ones the better-known games.

Mount & Blade II: Bannerlord
Shared: Medieval · Strategy · RPG

Crusader Kings III
Shared: Medieval · Strategy · RPG

Stronghold: Definitive Edition
Shared: Real Time Tactics · Medieval · Strategy

Stronghold Crusader: Definitive Edition
Shared: Real Time Tactics · Medieval · Strategy

RimWorld
Shared: Base Building · Colony Sim · Strategy

Stronghold Crusader HD (2012)
Shared: Real Time Tactics · Medieval · Colony Sim

Age of Empires II (Retired)
Shared: Medieval · RTS · Strategy

Stronghold HD (2012)
Shared: Real Time Tactics · Medieval · Colony Sim

Kingdoms and Castles
Shared: Colony Sim · Base Building · Strategy

Mount & Blade: Warband
Shared: Medieval · RPG · Strategy

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

Survivalist: Invisible Strain
Shared: Colony Sim · Base Building · RTS

Going Medieval
Shared: Base Building · Colony Sim · Strategy

Banished
Shared: Colony Sim · Strategy · Medieval

Diplomacy is Not an Option
Shared: Medieval · Base Building · Colony Sim

Kingdoms Reborn
Shared: Colony Sim · Base Building · Strategy

Foundation
Shared: Medieval · Simulation · Strategy

Stranded: Alien Dawn
Shared: Base Building · Colony Sim · Strategy

They Are Billions
Shared: Base Building · Colony Sim · Strategy

Manor Lords
Shared: Base Building · Strategy · Simulation

Becastled
Shared: Base Building · Medieval · Strategy

Farthest Frontier
Shared: Medieval · Strategy · Colony Sim

Lessaria: Fantasy Kingdom Sim
Shared: RTS · Strategy · Colony Sim

Age of Empires III: Definitive Edition
Shared: Base Building · RTS · Strategy