Edited sentence: Historian Bruce Catton's work on the American Civil War also influenced Card heavily.In a commentary track for the 20th Anniversary audiobook edition of the novel, as well as in the 1991 Author's Definitive Edition, Card stated that 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.In his 1991 introduction to the novel, Card discussed the influence of Isaac Asimov's Foundation series on the novelette and novel.The original novelette Ender's Game provides a small snapshot of Ender's experiences in Battle School and Command School; the full-length novel encompasses more of  Ender's life before, during, and after the war, and also contains some chapters describing the political exploits of his older siblings back on Earth