
Beginning with Secret of Mana, Seiken Densetsu was subsequently "spun off" into its own series of action role-playing games distinct from Final Fantasy, with four titles released between 19.

Originally developed under the title Gemma Knights, the game was renamed Seiken Densetsu: Final Fantasy Gaiden (published in North America as Final Fantasy Adventure and in Europe as Mystic Quest). In 1991, Square reused the Seiken Densetsu trademark for an unrelated Game Boy action role-playing game directed by Koichi Ishii. The letter also suggested to consider placing an order on another upcoming Square role-playing game in a similar vein: Final Fantasy. In October 1987, customers who had placed orders were sent a letter informing them of the cancellation and had their purchases refunded. Although Square solicited pre-orders for the game, Kaoru Moriyama, a former Square employee, affirms that management canceled the ambitious project before it advanced beyond the early planning stages.


According to early advertisements, the game would consist of an unprecedented five floppy disks, making it one of the largest titles developed for the Famicom up until that point. Square trademarked Seiken Densetsu in 1989, intending to use it for a game project subtitled The Emergence of Excalibur, and led by Kazuhiko Aoki for the Famicom Disk System.
