Games like Universe999999
Games like Universe999999 include Totally Accurate Battle Simulator, Game Dev Tycoon, Prison Architect, RimWorld, and People Playground. We matched them by the tags players give Universe999999 on Steam (Simulation, Sandbox, 2D Platformer, Idler, and 2D): closest matches first, and among equally close ones the better-known games.

Totally Accurate Battle Simulator
Shared: Simulation · Sandbox · Strategy

Game Dev Tycoon
Shared: Simulation · Strategy · Indie

Prison Architect
Shared: Simulation · Sandbox · Strategy

RimWorld
Shared: Sandbox · Simulation · Strategy

People Playground
Shared: Sandbox · Simulation · 2D

Ages of Conflict: World War Simulator
Shared: Sandbox · Simulation · Idler

鬼谷八荒 Tale of Immortal
Shared: Simulation · Sandbox · 2D

Plague Inc: Evolved
Shared: Simulation · Strategy · Indie

Amazing Cultivation Simulator
Shared: Simulation · Sandbox · Strategy

The Scroll of Taiwu : Beyond The Dome
Shared: Sandbox · Simulation · Strategy

Mashinky
Shared: Simulation · Sandbox · Strategy

Reus
Shared: Simulation · Sandbox · Strategy

Banished
Shared: Simulation · Sandbox · Strategy

Automation - The Car Company Tycoon Game
Shared: Simulation · Sandbox · Strategy

Ultimate Epic Battle Simulator
Shared: Simulation · Sandbox · Strategy

WorldBox - God Simulator
Shared: Sandbox · Simulation · Indie

Cities: Skylines
Shared: Simulation · Sandbox · Strategy

Nodebuster
Shared: Simulation · Idler · Strategy

Spaceflight Simulator
Shared: Sandbox · Simulation · 2D

Dwarf Fortress
Shared: Simulation · Sandbox · Strategy

Noita
Shared: Sandbox · 2D · Indie

Doodle Empires
Shared: Simulation · Sandbox · Strategy

Your Only Move Is HUSTLE
Shared: Sandbox · 2D · Strategy

Kerbal Space Program
Shared: Simulation · Sandbox · Indie