For most of its running-time “Ender’s Game” is essentially a junior-league version of “Starship Troopers,” though one told with pompous seriousness rather than a sarcastic edge. But in the last reel it turns into a pint-sized session on the captain’s bridge of the Enterprise, complete with a ponderously humanistic concluding message. Handsomely mounted but silly and tedious, Summit Entertainment’s hoped-for successor to its “Twilight” behemoth is more likely to follow in the footsteps of “Tron.” Of course, the picture does have a built-in audience—the readers of the young adult novel by Orson Scott Card on which it’s based (and which has thus far spawned four sequels). But it’s unlikely to have much appeal beyond that fan base.

For those unacquainted with the book, in a future when humankind has just barely fought off an invasion by an insectoid race called the Formics, teen Ender Wiggin (Asa Butterfield) is a recruit being trained in Battle School to serve in the next generation of earth’s defenders against the aliens. The premise is that it’s been determined that youngsters will be more capable of handling the split-second reaction demands of modernistic space weaponry because of their familiarity with the electronic devices they use as a matter of course. (You might think that this notion panders to kids who can’t be pried from their smart phones and video games—and you’d be right.)

But of course digital dexterity isn’t enough. For true greatness a child must be possessed of an almost preternatural combination of intellect and instinct that’s the key to strategic brilliance; only such a prodigy will be capable of leading the terrestrial force against the Formics. Gruff General Hyrum Graff (Harrison Ford), who heads the selection and training process, is certain that Ender is The One, combining the strengths of the two older siblings who proved unequal to the task—his overly volatile, violent brother Peter (Jimmy “Jax” Pinchak) and his excessively compassionate sister Valentine (Abigail Breslin). Graff’s colleague Major Gwen Anderson (Viola Davis), who’s in charge of psychological testing, isn’t so sure.

Much of “Ender’s Game” is devoted to the training Wiggin undergoes to prove his mettle, in which Graff deliberately puts the lad into situations where he has to confront bullies like squad commander Bonzo Madrid (Moises Arias). But although many of his classmates dislike the cerebral but steely boy, he gradually builds a company of devoted friends around him—most notably pretty Petra (Hailee Steinfeld), best buddy Bean (Aramis Knight) and supportive Alai (Suraj Parthasarsthy). Even the initially hostile Bernard (Conor Carroll) is ultimately won over by Ender’s leadership skills. After his final training with the legendary Mazer Rackham (Ben Kingsley), who served as the Ender of the first invasion in the most literal sense, they will all join Wiggin on the bridge during what he’s told is his final test—a simulated assault on the Formic home planet. But though the adults have correctly assessed the boy’s military capabilities, it turns out that they don’t understand the extent of his humanity.

No effort has been spared to give the movie a gleaming futuristic look; in the happily non-3D cinematography of Donald M. McAlpine, the interiors of the Battle School, particularly the huge chamber in which teams of cadets face off against one another under zero-gravity conditions, are elaborate, if sterile, constructions. (The production designers are Sean Haworth and Ben Procter, and the supervising art director A, Todd Holland.) The sequences that dramatize Ender’s dreams, driven by a mind game he plays on a tablet device, as well as the flashbacks to the Formic invasion and the culminating assault the boy leads against the aliens, also have a degree of grandeur, though they never transcend their CGI origin to feel fully realistic. Moreover, they’re not helped by Steve Jablonsky’s score, the bass rumblings in which—at least in the Imax format—might make you think an earthquake in underway.

The chilliness of the movie’s visuals is matched by Butterfield’s performance, in which the still-scrawny (though now taller) star of “Hugo” exudes an almost perpetual air of cool impassivity even under the most threatening conditions. The other characters are more demonstrative, especially Ford’s anxious Graff and Davis’ even more concerned Anderson. And while Arias comes off awfully strong as Ender’s chief tormentor, the other young actors acquit themselves as well as their stock roles allow. As for Kingsley, he struts about with the ramrod posture of the ultimate military man—none of the goofiness of his turn in “Iron Man 3” here—and lets his full-face tattoo do most of the acting for him.

In the end “Ender’s Game” comes across as a striking-looking film that never achieves the epic quality the makers are evidently straining for. Instead it’s a futuristic parable about a bullied young boy’s inherent wisdom in a world dominated by adult fear and manipulation that comes across, at least in this adaptation, as oddly constricted and curiously dispassionate. (The morality of creating an army of child soldiers, for example, barely gets a passing mention.) Still, the book has its share of admirers, and they will certainly enjoy seeing it transplanted to the screen. Others are likely to wonder what all the fuss is about.