Games like Solar 2
Games like Solar 2 include Kerbal Space Program, Goat Simulator, Universe Sandbox, Space Engineers, and SPORE™. We matched them by the tags players give Solar 2 on Steam (Space, Indie, Casual, Sandbox, and Relaxing): closest matches first, and among equally close ones the better-known games.

Kerbal Space Program
Shared: Space · Sandbox · Simulation

Goat Simulator
Shared: Simulation · Sandbox · Casual

Universe Sandbox
Shared: Space · Sandbox · Simulation

Space Engineers
Shared: Space · Sandbox · Simulation

SPORE™
Shared: Sandbox · Space · Simulation

Garry's Mod
Shared: Sandbox · Casual · Physics

People Playground
Shared: Sandbox · 2D · Physics

Starbound
Shared: Space · Sandbox · Indie

No Man's Sky
Shared: Space · Open World · Sandbox

Potion Craft: Alchemist Simulator
Shared: Relaxing · Indie · Simulation

SpaceEngine
Shared: Casual · Space · Sandbox

Mountain
Shared: Indie · Casual · Simulation

Stardew Valley
Shared: Relaxing · Simulation · Sandbox

Totally Accurate Battle Simulator
Shared: Sandbox · Simulation · Indie

Endless Sky
Shared: Space · Simulation · Open World

House Flipper
Shared: Simulation · Relaxing · Sandbox

Universe Sandbox
Shared: Space · Sandbox · Simulation

Wobbly Life
Shared: Sandbox · Simulation · Casual

Spaceflight Simulator
Shared: Space · Sandbox · Simulation

Townscaper
Shared: Relaxing · Sandbox · Casual

Reassembly
Shared: Space · Sandbox · Indie

Zup! S
Shared: Indie · Casual · Relaxing

Hardspace: Shipbreaker
Shared: Space · Simulation · Sandbox

Game Dev Tycoon
Shared: Indie · Casual · Simulation

