http://wbpkh5001.17c.cn/html5/

gistfile1.js

function normal() {
  var color1, color1box, color2, color2box;

  var boxes = document.querySelectorAll('#box > span'), boxLen = boxes.length;
  for(var i = 0; i < boxLen; i++) {
    var box = boxes[i], color = box.style.backgroundColor;

    if(i == 0) {
      color1 = color;
      color1box = box;
    } else if(!color2) {
      if(color != color1) {
        if(i > 1) {
          box.click();
          setTimeout(normal);
          return;
        } else {
          color2 = color;
          color2box = box;
        }
      }
    } else {
      (color == color1 ? color2box : color1box).click();
      setTimeout(normal);
      return;
    }
  }
}

function start() {
  document.getElementById('box').style.display = 'none';
  normal();
}