Which 1982 arcade sequel stars Donkey Kong's son trying to rescue him?

The 1982 arcade sequel starring Donkey Kong’s son as he tries to rescue him is Donkey Kong Jr.

Released by Nintendo in 1982, Donkey Kong Jr. reverses the roles of the original game. Mario has captured Donkey Kong and locked him in a cage, so the player controls Donkey Kong Jr. as he climbs vines, chains, and ropes to reach the keys and free his father.

The sequel grew from unused ideas and level concepts developed during the creation of the first Donkey Kong. Shigeru Miyamoto had considered making Donkey Kong the playable character, but the large character sprite was difficult to maneuver. Nintendo instead introduced a smaller son, Donkey Kong Jr., while keeping the original Donkey Kong visible as the captive at the top of the screen.

The game contains four stages with distinct layouts and hazards, including Snapjaws, Nitpickers, and Sparks. After the final stage, Donkey Kong is freed and Mario flees. Donkey Kong Jr. is therefore not a Mario Bros. spin-off or a game starring Pauline; its central story is the rescue of Donkey Kong.