A Database Error Occurred

Error Number: 1055

Expression #2 of SELECT list is not in GROUP BY clause and contains nonaggregated column 'freegames4rest.games_category.category' which is not functionally dependent on columns in GROUP BY clause; this is incompatible with sql_mode=only_full_group_by

SELECT `game_id`, `category` FROM (`games_category`) WHERE `game_id` IN ('ancient_rome_2', 'cradle_of_egypt', 'golden_trails_2_lost_legacy', 'letters_from_nowhere_2', 'cradle_of_rome_2', 'letters_from_nowhere', 'the_island_castaway', 'golden_trails_the_new_western_rush', 'ancient_rome', 'vacation_mogul', 'romance_of_rome', 'cradle_of_persia', 'star_defender4', 'cradle_of_rome', 'star_defender_3', 'star_defender_2') GROUP BY `game_id`