What are the names of the publishers who published the oldest games?
name of publisher refers to publisher_name; the oldest game refers to min(release_year)
SELECT DISTINCT T3.publisher_name FROM game_platform AS T1 INNER JOIN game_publisher AS T2 ON T1.game_publisher_id = T2.id INNER JOIN publisher AS T3 ON T2.publisher_id = T3.id ORDER BY T1.release_year LIMIT 1