Ender's Game Asa Buttferfield, Harrison Ford, Hailee Steinfeld. Directed by Gavin Hood. Rated PG-13. Opens Friday.

Unlike most of the genre novels that have been adapted into would-be film franchises in recent years (thanks to the success of the Harry Potter and Twilight series), Ender’s Game is pure, old-fashioned science fiction, published in 1985 as the first book in a sprawling, multi-pronged series by author Orson Scott Card. Although its young protagonist may look like the next Harry Potter or Percy Jackson, his story is less about coming-of-age drama and more about the politics of warfare. Card’s novel is as philosophical as it is character-driven, and although some of the social commentary (including a prominent subplot) has been pared down or taken out, the movie still takes on serious issues alongside its effects-heavy action sequences.

Chief among them is the question of how much responsibility society can place upon children. The movie’s title character (Asa Butterfield of Hugo) is a preteen charged with training for military command, as an officer in humanity’s war against ant-like aliens known as Formics. Although the child characters have actually been aged forward a bit from the novel, there’s still a striking contrast between their youth and the burdens they’re given, allegedly because their minds are more adaptable to the split-second decisions of combat. As Ender advances through his training, under the tutelage of a rough, unforgiving commander (Harrison Ford, putting his grumpiness to good use), he alternately revels in and rejects the unbridled militarism that surrounds him.

Butterfield and the other young actors (including True Grit’s Hailee Steinfeld) sometimes come off as a bit awkward spouting the dialogue of war, but their youthful ungainliness is also part of the movie’s point. Although the special effects are outstanding, the movie’s ambivalence about war robs the big space battles of some of their power, and especially during the climax, the suspense is muted at best. That may mean that Ender’s Game will miss the opportunity to become the next big blockbuster franchise its studio hopes for, but screenwriter and director Gavin Hood deserves credit for putting in as much of the novel’s intellectual challenges as he can within the structure of a crowd-pleasing action movie.