Zelda II: The Adventure of Link, often shortend to "The Adventure of Link" or "Zelda II", is the second main installment of The Legend of Zelda series and the direct sequel to The Legend of Zelda.[note 1] It was originally released on the Family Computer Disk System in 1987 for Japan and on the Nintendo Entertainment System in 1988 internationally. While retaining many of the features of its predecessor, The Adventure of Link altered certain elements of gameplay, most notably affecting movement and combat. Traveling across a world map would lead to enemy encounters which took place on a side-scrolling field of play rather than the top down perspective for which the 2D part of the series became widely known for. It is one of, if not the most difficult games of the franchise. Because of this, although it was successful like the previous title with 4.39 million copies sold, The Adventure of Link was met with mixed reactions by fans to this day and its gameplay concept for Zelda was controversial. Since A Link to the Past for the Super NES in 1991, side-scrolling was very rarely used for the series.