On November 1st, the film adaptation of Orson Scott Card's sci-fi novel Ender’s Game (Summit and OddLot, November 2013; PG-13) opened to mostly positive critical response and a $28 million domestic box office take. For the most part, the film succeeds as a condensed adaptation, even though it lacks some of the philosophical punch of the novel and rushes headlong toward its conclusion.

Young genius Ender Wiggin (Asa Butterfield) has grown up in a future where humanity lives in fear of invasion by the Formics, insect-like aliens that nearly defeated mankind in the past. To combat this imminent threat, the planet-wide International Fleet (I.F.) monitors every child to determine his or her suitability for Battle School, an orbiting space station that serves as a training ground for soldiers in the coming war. After Ender brutally retaliates against a bully’s attack to prevent future assaults, I.F. officers Colonel Graff (Harrison Ford) and Major Anderson (Viola Davis) offer him a place in Battle School, believing Ender to be the last, best hope to lead humanity’s forces. Ender accepts and quickly rises through the ranks in the zero-gravity mock battles, gaining friends and enemies. But the endgame is fast approaching, and Ender must face his greatest challenge or risk the future of the human race.

Inevitable divergences from the source material will be apparent to fans of the book. In the novel, Ender ages from six to eleven while in training, whereas the film Ender is a teenager through the course of the story. The movie also condenses Ender’s years of Battle School into weeks or months, and he breezes through the challenges like a wunderkind. Viewers are deprived of the depth of Ender’s isolation and frustration so richly explored in the novel. Although the movie thoughtfully addresses philosophical questions of war, it eliminates the book’s ideological debates between Ender’s brother and sister, the simmering tension of Earthbound politics, and the broader consequences of the story’s climax.

Despite these changes, the film works, due in large part to a well-chosen cast. Fresh off a winning performance as the title character in another big-budget children’s book adaptation (2011’s Hugo, based on Brian Selznick's The Invention of Hugo Cabret), Butterfield drives the film as a compelling Ender, by turns resolute and vulnerable. The other young actors also give strong performances, especially Hailee Steinfeld (True Grit) as fellow student Petra. As for the high-profile adult cast, Harrison Ford does his gruff military best, while conveying the weariness of a man whose life has been overshadowed by the looming prospect of apocalyptic war. Viola Davis is the staff’s sole voice of compassion, questioning the ethics of training child-warriors even as she authorizes mind games that threaten Ender’s emotional health. Ben Kingsley (another Hugo alum) plays the enigmatic master tactician Mazer Rackham with a tangible sense of power simmering beneath the surface.

Along with these solid performances, the special effects are the stars of this film. The book’s descriptions of formations and maneuvers were sometimes tedious and hard to visualize, but the film medium serves these moments well, beautifully realizing the weightless battle room skirmishes, swarming Formic armadas, and the human space fleet. The battle room is particularly impressive, depicted as an enormous spherical arena with the rotating Earth visible through its glass and steel framework. Even smaller details like the 3D hologram displays and computer interfaces flesh out the futuristic world of the movie.

In short, Ender’s Game has a few hiccups, but ultimately delivers on the spirit, if not the letter, of its literary roots.

Read Horn Book editor-in-chief Roger Sutton's thoughts on the film here.