Short answers, pulled from the story.
Cecil Harvey is the main character in Final Fantasy IV. He begins as a dark knight and captain of the Red Wings before transforming into a hero seeking redemption after questioning the King of Baron's motives.
Final Fantasy IV was released in 1991. Japanese reviewers gave it scores of 9, 9, 10, and 8, making it one of the highest-rated games of 1991.
Zemus is the true antagonist in Final Fantasy IV. He is a Lunarian who sought to destroy the Blue Planet to make room for his people and whose will grew stronger to twist men with tainted hearts into beings of darkness.
Nobuo Uematsu composed the music for Final Fantasy IV. He spent sleepless nights in sleeping bags at Square's headquarters to create the score, which has been praised as one of the greatest in video game history.
The Active Time Battle system in Final Fantasy IV is a combat mechanic that forces players to make snap decisions in real-time. This innovation was conceived by Hiroyuki Ito while watching a Formula One race and allows characters to act at different speeds.
The sequel to Final Fantasy IV is called Final Fantasy IV: The After Years. It is set seventeen years after the original events and focuses on Ceodore, the son of Cecil and Rosa.