Final Fantasy Tactics is generally considered to be one of the best SRPG of all time. Born out of the 32-bit era, Tactics not only brought Ivalice into the world, the connected universe that's shared by myriad Squaresoft games, but it also helped redefine the entire SRPG space in a post-Tactics Ogre world.
It was popular enough to warrant several ports and even a PSP remake, but its sequels ended up getting sent off to the GBA and DS instead of a proper console. According to its director Yasumi Matsuno though, there was a full sequel slated for the original PlayStation. Dubbed Final Fantasy Tactics 2, the project was planned and was even at the point where it had assets (that Matsuno has released).
Unfortunately due to complications with whether or not to outsource the game and confusion with a swap from 3D to a 2D hexagon-based visual style, the project was canceled. While this isn't the entire story, what's crazy is that Square didn't just...re-create the original with a new narrative? Square has always struggled somewhat capturing lightning in a bottle with followups, and this anecdote helps explain why.