Kerbal Space Program has no official multiplayer, but KSP 1 PC players can use mods. See the options, setup steps and common connection fixes.
Kerbal Space Program does not include official multiplayer. On PC, KSP 1 can be played cooperatively through community mods such as Luna Multiplayer or DarkMultiPlayer, with every player using a compatible game build and mod set. Console editions cannot use these mods, and KSP 2 never received its planned multiplayer mode.
Which Kerbal Space Program versions support multiplayer?
An unmodified KSP installation has no multiplayer button, shared server browser or split-screen mode. Multiplayer availability depends on the game version and platform:
| Version and platform | Multiplayer status | Practical option |
|---|---|---|
| KSP 1 on PC | Unofficial multiplayer available | Install Luna Multiplayer or DarkMultiPlayer and connect to a compatible server. |
| KSP 1 on console | No multiplayer | Console editions cannot install the required PC mods. |
| KSP 2 on PC | No released multiplayer mode | The planned official feature was never shipped; KSP 1 remains the practical choice for modded multiplayer. |
Luna Multiplayer and DarkMultiPlayer both provide a client plug-in and separate server software. They synchronise a shared universe, vessels and player activity, but each computer still runs KSP's physics locally. This is not a shared-cockpit mode: players normally control separate vessels, then meet, dock or work on the same mission.
Choose a mod according to support for your exact KSP build and required add-ons, not an old recommendation that may refer to another release. Starting with stock KSP is the quickest way to prove that the connection works.
How do you set up KSP multiplayer on PC?
- Match the KSP version. Every player should use the same KSP 1 build. The server package and client plug-in must also come from the same compatible multiplayer-mod release.
- Back up the game and saves. A separate, clean KSP installation is safest. Do not use the only copy of a long-running career as multiplayer test data.
- Install the client plug-in. Extract the multiplayer mod into the KSP directory so its plug-in folder sits directly under
GameData. A path resemblingGameData/GameData/...means it was installed one level too deep. Do not install Luna Multiplayer and DarkMultiPlayer together. - Make the mod lists identical. Players sharing modded craft need the same part packs, dependencies and relevant downloadable content. Test with only the multiplayer plug-in before adding visual, physics or part mods.
- Start the matching server. Keep the server files in their own folder, select the server's port and gameplay options, then launch it. The server can run on one player's PC or another reachable computer.
- Configure the network. LAN players connect using the host computer's local address. Internet hosting normally requires the chosen server port to be permitted through the operating-system firewall and forwarded by the router. Carrier-grade NAT can prevent ordinary inbound port forwarding.
- Connect and test. Enter the server address and configured port in the multiplayer plug-in. Launch simple stock vessels first; add the group's full mod set only after everyone can join and synchronise reliably.
How does time warp work in KSP multiplayer?
Multiplayer mods handle time warp through server-controlled rules such as independent time subspaces, synchronisation or group approval. The precise choices depend on the mod and server configuration.
Independent subspaces let one player accelerate time without forcing everyone else to warp, but those players can then occupy different points in game time. Before rendezvous, docking or formation flight, everyone should synchronise to the same subspace and stop warping. Synchronisation generally moves a player forward rather than rewinding the rest of the server.
This is the biggest adjustment for new KSP multiplayer groups. Agreeing who may warp during launches, atmospheric flight and close approaches prevents many apparent position errors and collisions.
Why can't players connect to the KSP server?
- Connection timed out: confirm that the server is running, the address and port are correct, and the firewall and router permit inbound traffic. A public Internet player cannot connect using the host's private LAN address.
- Server rejected the client: check the exact KSP build and multiplayer plug-in release. An outdated or duplicated plug-in is a common cause.
- Mod-control error: make every client's mod list and dependencies match the server rules. Begin with stock KSP if the rejected add-on is unclear.
- Craft contains unknown parts: every player who must load or control that craft needs the relevant part content. Replace unsupported parts or align the installations.
- Vessels jump, jitter or break during docking: synchronise time first, avoid warp, reduce network latency where possible and let one player control the final approach. Large, flexible craft amplify KSP's physics and synchronisation problems.
- Progress appears to roll back: use automatic server backups where the mod provides them. Quicksave, revert and career-resource behaviour can differ from ordinary single-player saves.
Can you play KSP multiplayer locally or on console?
KSP has no local split-screen multiplayer. A LAN game still requires a separate PC installation and multiplayer client for each player, although one of those computers may also host the server.
Console editions cannot install KSP 1's multiplayer plug-ins, so there is no equivalent workaround on console. If native multiplayer is essential, our comparison of simulator games designed for playing with friends separates built-in modes from community workarounds. For an aviation alternative, see which titles provide supported online flight-simulator multiplayer.