crea el juego de la culebrita

function playSnake(){
  //create the canvas 
  var canvas = document.createElement("canvas");
  var ctx = canvas.getContext("2d");
  canvas.width = 512;
  canvas.height = 480;
  document.body.appendChild(canvas);
  
  //background image
  var bgReady = false;
  var bgImage = new Image();
  bgImage.onload = function () {
    bgReady = true;
  };
  bgImage.src = "images/background.png";
  
  //snake
  var snakeReady = false;
  var snakeImage = new Image();
  snakeImage.onload = function () {
    snakeReady = true;
  };
  snakeImage.src = "images/snake.png";
  
  //food
  var foodReady = false;
  var foodImage = new Image();
  foodImage.onload = function () {
    foodReady = true;
  };
  foodImage.src = "images/food.png";