An entertainment system comprises parameter changing means for permitting a
user to input manipulation data by successively pressing a decision button
when a button icon is displayed on a display monitor. Based on the
manipulation data, the parameter changing means changes damage of a
virtual enemy (e.g., monster). The parameter changing means comprises
button icon displaying means for displaying the button icon on the display
monitor for a predetermined period of time, accumulating means for
counting the number of times the decision button is pressed for inputting
manipulation data when the button icon is displayed on the display
monitor, and damage calculating means for changing damage of the monster
based on the counted number of times.
