In which regions has the game 'Pengo' been sold?
which regions refers to region_name; 'Pengo' refers to game_name = 'Pengo';
SELECT T5.region_name FROM game AS T1 INNER JOIN game_publisher AS T2 ON T1.id = T2.game_id INNER JOIN game_platform AS T3 ON T2.id = T3.game_publisher_id INNER JOIN region_sales AS T4 ON T3.id = T4.game_platform_id INNER JOIN region AS T5 ON T4.region_id = T5.id WHERE T1.game_name = 'Pengo'