You could do it a few different ways.
Here's a couple off the top of my head:
$sql = "SELECT COUNT(column) AS games_played FROM table WHERE column > 0";
$result = mysql_query($sql) or die ("Could not execute query: ".mysql_error());
$row = mysql_fetch_object($result);
echo $row->games_played;
or
$sql = "SELECT column FROM table WHERE column > 0";
$result = mysql_query($sql) or die ("Could not execute query: ".mysql_error());
$count = mysql_num_rows($result);
echo $count;