var gameURL:String = "http://website.com";
var jscommand:String = "window.open('"+gameURL+"','win','width=800,height=596,toolbar=no,scrollbars=no,location=no,status=no,menubar=no');";
var url:URLRequest = new URLRequest("javascript:" + jscommand + " void(0);");
navigateToURL(url, "_self");