The Legend of Zelda: Majora's Mask 3D is the 2015 Nintendo 3DS remake of Majora's Mask, the 2000 Nintendo 64 sequel to Ocarina of Time. It was made by Grezzo, who also remade Ocarina of Time for the 3DS, and released in February 2015.
Link has three days to stop the Moon from crashing into Termina, reliving them again and again with the Song of Time. The 3DS version keeps that loop but changes a lot around it. Saving now happens at Owl and Quill Statues, the Song of Double Time skips to any hour you choose, and the Bombers' Notebook was rebuilt with alarms and rumors. The bosses were redesigned, and there are two new Fishing Holes and a seventh bottle. Our What's New page lists every change.
Our guides cover the 3DS version: all 52 Heart Pieces (one moved), the seven bottles and the new Fishing Holes. For masks, the Bombers' Notebook and the rest, our original Majora's Mask guides still apply.