I don't know much about the internals of server-side games, like CSS, but I think they use things called frames that contain all the world information. Everyone gets sent the frames a certain amount of times per second (hence 66 tickrate servers in CSS). Also from playing the BF2142 demo (which keeps disconecting you), you can tell the server is giving you a movement velocity and also a rotation velocity about each player (you see tanks spin slowly around a point downward into the ground! during "connection problem"). So what am I getting at? To be a truly versatile engine it must support trace hit weapons. By this I mean things like guns. SS only has projectile weapons. I would imagine tracehit client side would be awful since everyone plays "in the future", ships can easily be more than 1 ship length out of place. I think one problem with moving stuff server side is you need low pings for players to see everything smoothly, we would need more servers in different countries.