Games like KAIWorld
Games like KAIWorld include People Playground, Garry's Mod, Stardew Valley, Terraria, and Cities: Skylines. We matched them by the tags players give KAIWorld on Steam (Casual, Simulation, Sandbox, 2D, and Pixel Graphics): closest matches first, and among equally close ones the better-known games.

People Playground
Shared: Sandbox · 2D · Simulation

Garry's Mod
Shared: Sandbox · Casual · Building

Stardew Valley
Shared: Pixel Graphics · Simulation · Sandbox

Terraria
Shared: Sandbox · 2D · Pixel Graphics

Cities: Skylines
Shared: Simulation · Sandbox · Building

House Flipper
Shared: Simulation · Casual · Sandbox

Graveyard Keeper
Shared: Simulation · Pixel Graphics · Sandbox

The Sims™ 4
Shared: Simulation · Building · Sandbox

Prison Architect
Shared: Simulation · Sandbox · Building

Planet Coaster
Shared: Simulation · Sandbox · Building

The Sims™ 3
Shared: Simulation · Sandbox · Casual

Project Highrise
Shared: Simulation · Building · 2D

Cities: Skylines II
Shared: Simulation · Sandbox · Building

DAVE THE DIVER
Shared: Casual · Pixel Graphics · Simulation

Game Dev Tycoon
Shared: Simulation · Casual · 2D

TheoTown
Shared: Simulation · Sandbox · Pixel Graphics

Two Point Hospital
Shared: Simulation · Building · Sandbox

Oxygen Not Included
Shared: Building · 2D · Sandbox

PC Building Simulator
Shared: Simulation · Sandbox · Building

WorldBox - God Simulator
Shared: Sandbox · Simulation · Pixel Graphics

Townscaper
Shared: Sandbox · Casual · Building

SUMMERHOUSE
Shared: Sandbox · Casual · Singleplayer

Goat Simulator
Shared: Simulation · Sandbox · Casual

Space Engineers
Shared: Sandbox · Simulation · Building