<div id="wrap">
  <p>move the cursor around the screen</p>
</div>
@import url(https://fonts.googleapis.com/css?family=Open+Sans);

html, body {
  height: 100%;
  margin: 0;
  position: relative;
  background: #222;
  font-family: "Open Sans";
}

#wrap {
  width: 100%;
  height: 100%;
  position: relative;
  overflow: hidden;
}

#wrap p {
  position: absolute;
  left: 50%;
  top: 50%;
  transform: translateX(-50%) translateY(-50%);
  color: rgba(255,255,255,.5);
  font-size: 30px;
  text-transform: uppercase;
  letter-spacing: 5px;
  text-align: center;
}

.ball {
  pointer-events: none;
  position: absolute; 
  width: 10px;
  height: 10px;
  border-radius: 50%; 
  background: gray;
  animation: implode 1s ease-in-out;
  animation-fill-mode: both;
  opacity: .5;
}

@keyframes implode {
  100% {transform: scale(0)}
}
View Compiled
$(document).ready(function(){
  
  var mousePos = {};

 function getRandomInt(min, max) {
   return Math.round(Math.random() * (max - min + 1)) + min;
 }
  
  $(window).mousemove(function(e) {
    mousePos.x = e.pageX;
    mousePos.y = e.pageY;
  });
  
  $(window).mouseleave(function(e) {
    mousePos.x = -1;
    mousePos.y = -1;
  });
  
  var draw = setInterval(function(){
    if(mousePos.x > 0 && mousePos.y > 0){
      
      var range = 15;
      
      var color = "background: rgb("+getRandomInt(0,255)+","+getRandomInt(0,255)+","+getRandomInt(0,255)+");";
      
      var sizeInt = getRandomInt(10, 30);
      size = "height: " + sizeInt + "px; width: " + sizeInt + "px;";
      
      var left = "left: " + getRandomInt(mousePos.x-range-sizeInt, mousePos.x+range) + "px;";
      
      var top = "top: " + getRandomInt(mousePos.y-range-sizeInt, mousePos.y+range) + "px;"; 

      var style = left+top+color+size;
      $("<div class='ball' style='" + style + "'></div>").appendTo('#wrap').one("webkitAnimationEnd mozAnimationEnd MSAnimationEnd oanimationend animationend", function(){$(this).remove();}); 
    }
  }, 1);
});

External CSS

This Pen doesn't use any external CSS resources.

External JavaScript

  1. https://cdnjs.cloudflare.com/ajax/libs/jquery/2.1.3/jquery.min.js