Sakaguchi's initial script and story idea was for a detective story that took place in modern day New York.

The urban setting became midgar, the other ideas were later developed into Parasite Eve.

Of the many pitches made for the FFVII story, one by a certain Tetsuya Takahashi was for a game with philosophical themes, psychologically dense characters, religious motifs, and big mechs. This pitch was rejected and eventually greenlit for its own project, Xenogears.

Chrono Trigger was initially a project meant to be worked on while they began working on FF7, but the CT team needed more help so work on FF7 was delayed. As a result, many ideas intended for 7 then were bled into CT. My personal hypothesis lies in the parallel between JENOVA and Lavos as parasitic planet-threatening life forms, the concept of the "entity" paralleling the lifestream, the unexpected loss of a major character being a major theme (although dealt in very different ways), some of the more sci-fi elements both games share especially with the atmosphere of the future era being a sort of testing ground for 7, and lastly, some of the final sidequests, particularly with Lucca, were written as last-minute additions to the story by Kitase and Sakaguchi indepently, might have been holdovers from the upcoming 7 project.

Several concepts, like raijin and fuujin and edea were meant for FF7 but went unused and were instead used in 8. Edea was an early concept for a character in 7, and her design can be seen as Nomura imitating the style of the previous character designer, Amano, and his signature flowy, intricate, and ornate approach to fashion. Once the technology and look of 7 became more finalized, a more sharp, simple, and pointy manga-like approach was chosen instead for its compatibility with the abilities of the ps1 real-time rendering capabilities.