The trebuchet was one of the most devastating weapons of the Middle Ages. During medieval sieges, this destruction machine crushed castle walls. Using trial and error, medieval engineers adjusted the trebuchet to make sure its missile hit the castle wall—and destroyed it.
NOVA's science game, "Destroy the Castle," is very much like the real thing. There are five elements you can adjust in your trebuchet:
stone ball weight
distance from the castle
whether to add wheels
Build it right, and you will crush the wall.
Build it wrong, though, and you may have to face some painful consequences.