Ys IV: The Game That Exists Twice
Falcom outsourced its own sequel to two companies at once, and both of them shipped.
For the fourth Ys, Falcom did something no other series has quite repeated: it prepared the setting, characters, and story outline, then licensed development to two different studios simultaneously. Hudson Soft built Ys IV: The Dawn of Ys for PC Engine CD; Tonkin House built Ys IV: Mask of the Sun for Super Famicom. Both released in 1993, same raw materials, two different games in one land, Celceta.
For nineteen years "Ys IV" meant whichever one your hardware played. Falcom settled the matter in-house with Ys: Memories of Celceta (2012), its own canonical remake of the Celceta story for the series' twenty-fifth anniversary, which is the version the modern timeline keeps.
THE TWO DAWNS
Same bible, different booksThe Dawn of Ys
Hudson's version plays like a direct sequel to Book I & II: bump combat, CD audio, and an early, expansive take on the Eldeen mythology.
Mask of the Sun
Tonkin House's Super Famicom version is leaner and stranger, its own reading of the same outline; it even received two separate manga adaptations, by Hitoshi Okuda and Nozomu Tamaki.
The lesson
Ys IV is the clearest proof of what a Falcom scenario actually is: strong enough material that two competent studios could build two different good games from the same brief.