The big difference between violin and say piano is that with a piano if you hit a key with a certain velocity it will make a certain sound. Over and over again. On the violin it isn't nearly that simple and just forming the tone will take a long time (in a way you never stop getting better at that).
http://forum.pianoworld.com/ubbthreads.php/topics/3139/can-a...
Each round one of the violinists plays a simple melody for one non-violinist member of the other team. Then that person takes the violin and tries to play it for another non-violinist member of their team and so until the last non-violinist plays it for the violinist on their team. If the violinist can identify the piece their team gets a point.
It also makes me wonder if I would be able to get any sound out of a violin today.