go to index.html then remove this part
<script>
// Issue a warning if trying to preview an exported project on disk.
(function(){
// Check for running exported on file protocol
if (window.location.protocol.substr(0, 4) === "file")
{
alert("Exported games won't work until you upload them. (When running on the file:/// protocol, browsers block many features from working for security reasons.)");
}
})();
</script>
then SAVE. i hope i helped you