colorscript.js

// stashes the box
var box = document.getElementById('box');
// Sets a 1 ms interval to call clickThemAll()
setInterval(clickThemAll, 1);
// Clicks the play button to start the game
document.querySelector('.play-btn').click();

function clickThemAll(){
  //grabs the children, sets prevBG to false, stores length
  var children = box.querySelectorAll('span')
    , prevBG = false
    , len = children.length
    ;

  for (i = 0; i < len; ++i) {
    // grabs the background
    var background = children[i].style.background;
    // checks if the background is different than the previous. If so, clicks.
    if (prevBG && prevBG !== background) {
      children[i].click();
    }
    // If none of them are different than the first one is the square to click
    else if (i === (len - 1)) {
      children[0].click();
    }
    // set the prevBG to the current background
    prevBG = background;
  }
}