These are really a lot of fun for a young child. The first step is to assemble the siege engines from the parts. (It’s mildly challenging.) The second step is to install the “driver” (the red rubber bands). The third is to load the projectiles and try to hit the targets – or better still the Dragon which is menacing your troops. The Catapult slings small wooden balls in an arc.
The Mechanical Crossbow (or Ballista as the Romans called it) shoots small arrow-like projectiles. (The balls are very light each weigh about 1/40th oz and the “arrows” about 1/16th oz so the primary enjoyment of these toys lies in their assembly and appearance. Best for a younger child.