10 space sandbox games on Steam with co-op or multiplayer, ranked by how many people are playing right now and how well they review. Part of Sandbox & building.
| Game | Modes | Type | Rating | Playing now | Price |
|---|---|---|---|---|---|
| Kerbal Space Program | Co-op, Single-player too | Space sandbox | 95% | 1,844 | $39.99 |
| NEBULOUS: Fleet Command | Co-op, PvP | Space sandbox | 82% | 212 | $29.99 |
| Star Trek: Infinite | PvP, Single-player too | Space sandbox | 43% | 31 | $7.49 |
| Heavenly Bodies | Co-op, Local / split-screen | Space sandbox | 96% | 19 | $19.99 |
| Star Sonata 2 | Online multiplayer | Space sandbox | 67% | 21 | Free |
| Istrolid | Co-op, PvP | Space sandbox | 87% | 6 | Free |
| Galactic Junk League | PvP | Space sandbox | 69% | — | |
| The Orville - Interactive Fan Experience | PvP, Single-player too | Space sandbox | 90% | 2 | Free |
| CSC | Space MMO | Online multiplayer | Space sandbox | 62% | — | |
| Slingshottr | Co-op, Single-player too | Space sandbox | 100% | — | $4.99 |
Ready Up is a free tool: enter two Steam usernames and it lists the multiplayer games you both own, runs a bracket to pick one, and suggests new co-op games that fit how you both play. Ratings, tags and player counts from Steam and SteamSpy; page updated 2026-09-23. Powered by Steam — not affiliated with or endorsed by Valve Corporation or Microsoft. Ready Up is a Somebody Decide program. How the data works · Legal & privacy · All types · Game Pass