IIRC, Card wrote Ender's Game in high school and later dusted it off, fixed it up, and published it.
https://en.wikipedia.org/wiki/Ender's_Game#Creation_and_insp...
> Ender's Game was written specifically to establish the character of Ender for his role of the Speaker in Speaker for the Dead, the outline for which he had written before novelizing Ender's Game.