I've just had an idea about how synchronization may be easier, though this is one of the first KSP Multiplayer threads I've read so it may have been suggested before... Anyway, couldn't it be viable to synchronize players relative to the body which they are influenced by? Time warp is a big issue, that has been established. If a player is to warp time, the planets on that client will be unsynchronized with the other clients' planets, right? However, the planet itself does not ever change. We could treat each planet as a 'room' with the boundaries determined by its sphere of influence, for example. The player(s) who enter the sphere of influence of that planet (or within a certain distance of it) will be synchronized with other players, and should they timewarp whilst in this 'room', it will just look like they are moving faster, like in the video. Their position would be stored local to the planet to make things simpler to synch. Obviously things such as time of day etc will not be synchronized, though the idea of playing with friends etc could still be achieved. I didn't spend long thinking about this so it might be flawed... It's just an idea. EDIT: Not sure if I made this clear, but it would not matter if the planets' positions were not synchronized. If each planet is treated as a room, someone sitting on that planet would just be able to see other players entering that room. I find it hard to describe this. Let's say a player creates a ship and heads towards the Mun. He flies close enough to have an encounter with the Mun. His client will then tell the server that he is joining the 'Mun Room' and so the server will send him information about any other players who are also in the 'Mun Room'.