Games like Island God Simulator
Games like Island God Simulator include Oxygen Not Included, RimWorld, Manor Lords, Conan Exiles Enhanced, and Kenshi. We matched them by the tags players give Island God Simulator on Steam (Strategy, RPG, Simulation, Singleplayer, and God Game): closest matches first, and among equally close ones the better-known games.

Oxygen Not Included
Shared: Base Building · Singleplayer · Building

RimWorld
Shared: Strategy · Base Building · Singleplayer

Manor Lords
Shared: Strategy · Simulation · Base Building

Conan Exiles Enhanced
Shared: Open World · Building · RPG

Kenshi
Shared: RPG · Open World · Simulation

Factorio
Shared: Strategy · Base Building · Sandbox

Mount & Blade II: Bannerlord
Shared: Strategy · RPG · Open World

Once Human
Shared: Open World · Building · Survival

Satisfactory
Shared: Base Building · Open World · Building

Against the Storm
Shared: Strategy · Simulation · Base Building

Raft
Shared: Open World Survival Craft · Survival · Building

7 Days to Die
Shared: Base Building · Open World · Survival

Space Engineers
Shared: Simulation · Building · Sandbox

Valheim
Shared: Open World Survival Craft · Open World · Building

Cities: Skylines
Shared: Simulation · Strategy · Building

Dyson Sphere Program
Shared: Base Building · Simulation · Building

Prison Architect
Shared: Simulation · Strategy · Building

Amazing Cultivation Simulator
Shared: Simulation · RPG · Strategy

The Scroll of Taiwu : Beyond The Dome
Shared: RPG · Strategy · Singleplayer

ARK: Survival Evolved
Shared: Open World Survival Craft · Open World · Building

Project Zomboid
Shared: Open World · Survival · Open World Survival Craft

Jurassic World Evolution
Shared: Simulation · Strategy · Building

Norland
Shared: Strategy · Simulation · Base Building

Jurassic World Evolution 2
Shared: Simulation · Strategy · Building