Ender in Exile is an "in between" novel that occurs between Ender's Game and the further novels in the series. It chronicles the time that occurs immediately after the formic war at the end of Ender's Game, covering things like deciding whether Ender should return to earth, and the first colonization of planets.

I usually don't enjoy novels where the author returns to the middle of an established time line to flesh out events, but this managed to do it without feeling unnecessary. It introduced a few interesting new characters, and events didn't feel like they were being hemmed in by existing canon.