Here is the essence of the competition: Construct a device that can shoot a hollow rubber ball (spherical, minimum diameter 3 cm) at a target located at a distance between 2 m and 8 m. Here is an applet that simulates the kinds of trajectories that the rubber balls can take.
You can select the inital angle and velocity of the projectile by clicking somewhere inside the white area. Once you have selected the combination you want, you press the start button.