It's time you become World Boxing Champion. To become champion you need to fight and defeat 8 fighters.
The game is viewed from the side showing your two fighters, referee and the crowd. To control your boxer you use the joystick. Moving it left and right moves your boxer left and right. Pushing up throws a punch to the head, pulling down throws a body punch. Pressing the fire button defends your head.
Every time you hit your opposition you get a point, likewise for him. Hit him enough and you knock him out. The referee counts to 10 and it's fight over.