A device is described for introducing variation in athletic training and competitive events. This device maintains an internal state that occupies one of several allowed values. Depending upon the selected configuration, the device changes internal state at regular or irregular intervals, progresses through its allowed values sequentially or in random order, and spends a different designated fraction of time in each state. This variable and typically unpredictable state is presented to the field of play where one or more athletes receive the information and react to it as a change in their athletic training or game environment.