A quick fix for those who have the error: Impossible to select the latest score.
This is a version problem of php 4.
Please edit arcade.php edit line 131:
$sql = 'SELECT game_name, username, rank_date, rank_score, id, game_id FROM '.$db->prefix.'arcade_ranking, '.$db->prefix.'arcade_games, '.$db->prefix.'users WHERE rank_game = game_filename AND '.$db->prefix.'users.id = rank_player GROUP BY rank_date ORDER BY rank_date DESC LIMIT 1';
and change it to:
$sql = 'SELECT game_name, username, rank_date, rank_score, id, game_id FROM '.$db->prefix.'arcade_ranking, '.$db->prefix.'arcade_games, '.$db->prefix.'users WHERE rank_game = game_filename AND '.$db->prefix.'users.id = rank_player GROUP BY rank_date ORDER BY rank_date DESC LIMIT 1';
This should fix the problem.