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An unidentified Gatling gun appears in the first chapter of Metroid Prime: Episode of Aether.
The Space Pirates, wielding Gatling guns and Pulse Cannons, take over the Crest ship and hold the crew and passengers hostage under the leadership of their boss. Samus Aran receives the distress call and rushes to the ship. The Pirates, believing they far outnumber Samus, all fire on her with their weapons, but she is able to miraculously avoid all of it. She picks up this Gatling gun from the ground (presumably dropped from a fallen Space Pirate) and fires it at her enemies in tandem with her Arm Cannon, much to their shock. After disposing of the Space Pirates, Samus drops the Gatling gun to the floor and then confronts the pirates' boss.
The presence of a Gatling gun, a World War II invention that has been replaced by machine guns, in the futuristic Metroid universe appears to be an unusual anachronism.