Games like simple shapes
Games like simple shapes include People Playground, Garry's Mod, Totally Accurate Battle Simulator, Goat Simulator, and Game Dev Tycoon. We matched them by the tags players give simple shapes on Steam (Simulation, Physics, Sandbox, 2D, and Singleplayer): closest matches first, and among equally close ones the better-known games.

People Playground
Shared: Sandbox · Physics · 2D

Garry's Mod
Shared: Sandbox · Physics · Casual

Totally Accurate Battle Simulator
Shared: Simulation · Sandbox · Physics

Goat Simulator
Shared: Simulation · Sandbox · Physics

Game Dev Tycoon
Shared: Simulation · Singleplayer · Casual

Poly Bridge
Shared: Physics · Simulation · Sandbox

Kerbal Space Program
Shared: Simulation · Sandbox · Physics

Bridge Constructor Portal
Shared: Simulation · Physics · Singleplayer

Potion Craft: Alchemist Simulator
Shared: Simulation · Singleplayer · 2D

BeamNG.drive
Shared: Simulation · Physics · Sandbox

Space Engineers
Shared: Sandbox · Simulation · Physics

鬼谷八荒 Tale of Immortal
Shared: Simulation · Singleplayer · Sandbox

Zup! S
Shared: Physics · 2D · Casual

Teardown
Shared: Physics · Sandbox · Singleplayer

Mutilate-a-Doll 2
Shared: Physics · Sandbox · Simulation

Noita
Shared: Physics · Sandbox · 2D

Besiege
Shared: Simulation · Physics · Sandbox

Happy Wheels
Shared: Physics · Sandbox · 2D

A Dance of Fire and Ice
Shared: Singleplayer · 2D · Level Editor

Plague Inc: Evolved
Shared: Simulation · Singleplayer · Indie

Slime Rancher
Shared: Singleplayer · Simulation · Sandbox

Wobbledogs
Shared: Simulation · Sandbox · Colorful

House Flipper
Shared: Simulation · Singleplayer · Sandbox

Cooking Simulator
Shared: Simulation · Sandbox · Singleplayer