Seiken Densetsu: The Emergence of Excalibur

Seiken Densetsu: The Emergence of Excalibur, originally known simply as Excalibur, is a cancelled action role-playing game for the Famicom Disk System that was developed by Square, during a time when the company led a union known as the Disk Original Group (DOG). It would have been the first Seiken Densetsu title.

The "Seiken Densetsu" name would not be used again until 1991 when Square released Seiken Densetsu: Final Fantasy Gaiden for the Game Boy, also known as Final Fantasy Adventure in North America and Mystic Quest in Europe; this would later serve as the start of Square's (later Square Enix's) Mana series of role-playing games.