1 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.
Which of these do we both own? →
| Game | Modes | Type | Rating | Playing now | Price |
|---|---|---|---|---|---|
| Kerbal Space Program | Co-op, Single-player too | Space sandbox | 95% | 1,844 | $39.99 |
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; updated 2026-09-08. Powered by Steam — not affiliated with or endorsed by Valve Corporation.