<title>Contagem regressiva</title>
<?php
if($_GET['t'] == '0'){
    print "Tempo esgotado.";
}else{
    $t = $_GET['t'];
    $t = $t-1;
    print $t;
    print "<meta HTTP-EQUIV='refresh' CONTENT='1;URL=test.php?t=". $t ."'>";
}
?>