Games like Atomic Playground
Games like Atomic Playground include Kerbal Space Program, Universe Sandbox, Kerbal Space Program 2, Spaceflight Simulator, and Universe Sandbox. We matched them by the tags players give Atomic Playground on Steam (Simulation, Science, Sandbox, Early Access, and Education): closest matches first, and among equally close ones the better-known games.

Kerbal Space Program
Shared: Simulation · Sandbox · Science

Universe Sandbox
Shared: Simulation · Sandbox · Science

Kerbal Space Program 2
Shared: Sandbox · Science · Simulation

Spaceflight Simulator
Shared: Sandbox · Simulation · Science

Universe Sandbox
Shared: Simulation · Sandbox · Science

Solar Expanse - Space Exploration Manager
Shared: Simulation · Sandbox · Science

Totally Accurate Battle Simulator
Shared: Simulation · Sandbox · Physics

Space Engineers
Shared: Sandbox · Simulation · Physics

BeamNG.drive
Shared: Simulation · Physics · Sandbox

SpaceEngine
Shared: Sandbox · Science · Space

SPORE™
Shared: Sandbox · Simulation · Science

Aviassembly
Shared: Sandbox · Physics · Simulation

Garry's Mod
Shared: Sandbox · Physics · Simulation

People Playground
Shared: Sandbox · Physics · Simulation

Goat Simulator 3
Shared: Sandbox · Simulation · Physics

Goat Simulator
Shared: Simulation · Sandbox · Physics

PC Building Simulator
Shared: Simulation · Education · Sandbox

Poly Bridge
Shared: Simulation · Physics · Sandbox

Empyrion - Galactic Survival
Shared: Simulation · Space · Sandbox

Hardspace: Shipbreaker
Shared: Simulation · Physics · Sandbox

Space Engineers 2
Shared: Sandbox · Simulation · Space

Flyout
Shared: Simulation · Sandbox · Physics

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

Teardown
Shared: Sandbox · Physics · Indie