Short answers, pulled from the story.
Final Fantasy Legend III follows four warriors from two races who travel through time to stop the Water Entity, a non-sentient force summoned by the dimensional realm of Pureland. The party collects parts for the Talon ship to move between eras and eventually destroys the entity by killing the god Sol and the primal water deity Xagor.
Final Fantasy Legend III was developed by a newly-founded Square studio in Osaka with Chihiro Fujioka as the producer. Series creator Akitoshi Kawazu was not involved in the project because he was occupied with developing Romancing SaGa.
Final Fantasy Legend III was released under its SaGa 3 title by Square in Japan on the 13th of December 1991. Two guidebooks were published by NTT Publishing in December 1991 and January 1992.
Players choose from two races, humans and mutants, who gain experience points or use skills to level up. Characters can evolve into monster or robot classes by using items like meat or mechanical parts gained from enemies.
The Collection of SaGa Final Fantasy Legend was released for Android and iOS on the 22nd of September 2021. It was later released for Microsoft Windows through Steam on October 21.
As of 2002, Final Fantasy Legend III had sold 650,000 units, making it the third best-selling title of the Game Boy SaGa releases. It was also the lowest-selling original SaGa title as of that time.