Conversion des secondes en HH:MM:SS

Utilisez la fonction MySQL SEC_TO_TIME.

Exemple :

mysql> SELECT SEC_TO_TIME(2378);
        -> '00:39:38'

Vous pouvez donc écrire votre requête SQL comme :

SELECT username, score, SEC_TO_TIME(timeran) as timetaken FROM gamescores ORDER BY Time DESC

Votre code devient alors :

<?php
$result = mysql_query("SELECT username, score, SEC_TO_TIME(timeran) as timetaken FROM gamescores ORDER BY Time DESC");
if (mysql_num_rows($result)) {
for($rank=1; $row = mysql_fetch_assoc($result); $rank++) {
    echo "<tr>
    <td>{$rank}</td>
    <td>{$row['username']}</td>
    <td>{$row['timetaken']}</td>
    <td>{$row['score']}</td>