I recently looked into this myself, the 'setting up' part of the process is already described here: http://wiki.kerbalspaceprogram.com/wiki/Setting_up_MonoDevelop. MonoDevelop is now 'Xamarin Studio' which was confusing for me at first, but it works fine. Install Xamarin Studio and the prerequisites. Next, get the code at https://github.com/TehGimp/KerbalMultiPlayer: click 'Download ZIP' at the right. You may want to try a different branch instead of the master branch, see 'branches' in the top menu. Open the .sln file from the zip in Xamarin Studio, it should show you three projects: KerbalMultiPlayer, KMPServer and KMPServerList. We want the first (client) and second (server) project to build. Under 'References' for both client and server you'll see a number of items coloured in red. These are references that weren't found and which we'll need to add ourselves: - delete the red-coloured reference - edit references, go to the .Net Assembly tab and browse to your KSP_win\KSP_Data\Managed folder. > for 'Assembly-CSharp', add Assembly-CSharp.dll. > for 'Assembly-CSharp-firstpass', add Assembly-CSharp-firstpass.dll. > for 'UnityEngine, add UnityEngine.dll Set the target to 'Release' instead of 'Debug' in the top left dropdown and choose Build > Build All. If your prerequisites are in order, you should now have everything built without errors (there may be warnings). You'll find a brand new KerbalMultiPlayer.dll and KMPServer.exe in the bin\Release folder of the corresponding project. No doubt there's an easier way to do the above, but it works for me .