1. An apparatus for propelling a projectile for an action by a user, the apparatus comprising: an impeller for receiving a projectile and projecting it along an impeller axis; detecting means for detecting a command signal corresponding to one of a gesture made by the user and a sound made by the user; data processing means operatively connected to the detecting means for determining a projection axis and projection speed according to at least ballistic characteristics of the projectile and the detected command signal; impeller control means responsive to the data processing means and operatively connected to the impeller for adjusting: impeller projection speed according to the determined projection speed, and impeller position to conform the impeller axis with the determined projection axis; and a feed mechanism for introducing a projectile into the impeller for projection.