Making the Paddle Work

// Declare gameOperators  These will be updated.
var paddleLeft;

/** Declare Update & Draw Functions outside Draw Loop */
var updatePaddle = function(){
    paddleLeft = mouseX - PADDLE_WIDTH / 2;
};
var drawPaddle = function(){
    rect(paddleLeft, PADDLE_TOP, PADDLE_WIDTH, PADDLE_HEIGHT);
};

//The all important: draw = function(){ };

draw = function(){  // Begin Draw Loop
background(0); 

/** Call Update & Draw Functions inside Draw Loop */
updatePaddle();
drawPaddle();
    
}; // End Draw Loop

Another form of Detection

/** If the Ball goes Offscreen */
if(ballPositionY > 420){ 
playerLives -= 1; // Subtract 1 from Number of Plays
ballPositionY = 30; // Reposition Ball for next serve
    }
  
/** Print the playerLives Variable  to the screen **/
text("Lives left: " + playerLives, 40, 50);

Adding a Scoring System

/** Print the playerLives Variable to the screen **/ text("Lives left: " + playerLives, 40, 50); score++; text("Ponts earned = " + score, 290, 50);

Ending the Game

Adding a Background image.

//Load Backround for end of Game
PImage bg_img; 
void setup() 
{ 
   size(400, 400);
   bg_img = loadImage("vintage(400).jpg"); 
} 
 
//PAU GAME
if(playerLives === 0) {
    //background(0, 0, 255);
	image(bg_img);
	fill(0, 0, 255);
    textSize(36);
	textAlign(CENTER);
    text("Pau Game", 200, 100);
    textSize(24);
	textAlign(CENTER);
    text("But you did Score: " + score, 200, 125);
    noLoop();
}

}; // End Draw Loop