/vr/ - Retro Games

Seiken Densetsu: The Emergence of Excalibur ranks pretty high. It was a Disk System RPG spanning FIVE DISKS that Square was going to release before they placed their bets on the first (D&D-inspired) Final Fantasy. The game was entirely canned, with the Seiken Densetsu trademark going to an unrelated Final Fantasy spinoff years later (which in turn spun into the Mana series). I wonder how far this one got along, since the reason for cancellation seems to be because the Disk System lost relevancy. Given how iconic to the genre Square's pre-merger RPGs are, there's a certain mystique about a lost classic that could have been.

The original Final Fantasy IV on Famicom ranks as a distant second, but last I heard (and don't quote me), it was reborn and became Final Fantasy Dimensions. And of course, there's Chrono Break, but I don't think any work got done on that at all besides trademark filing.