How many games were released on PS4 in 2014?
on PS4 refers to platform_name = 'PS4'; in 2014 refers to release_year = 2014
SELECT COUNT(DISTINCT T3.game_id) FROM platform AS T1 INNER JOIN game_platform AS T2 ON T1.id = T2.platform_id INNER JOIN game_publisher AS T3 ON T2.game_publisher_id = T3.id WHERE T1.platform_name = 'PS4' AND T2.release_year = 2014