function openGame() {
var win = window.open ()
var url = "https://hateroll.com"
var iframe = win.document.createElement('iframe')
 iframe.style.position = "fixed";
  iframe.style.top = 0;
  iframe.style.bottom = 0;
  iframe.style.left = 0;
  iframe.style.right = 0;
  iframe.style.border = "none";
  iframe.style.outline = "none";
  iframe.style.width = "100%";
  iframe.style.height = "100%";
  iframe.src = url;
win.document.body.appendChild(iframe)
}

<script defer data-domain="html.cafe" src="https://milkymouse.com/js/script.js"></script>