The book ‘Ender’s Game’, by Orson Scott Card, stands as one of the best sci-fi titles ever written, which has made turning its sweeping story of alien invasion and complex simulations into a film that retains the heart and ethical dilemma faced by the main character, Ender Wiggin, a daunting task. Rumors of cinematic adaptations have swirled around the industry for almost 25 years.

With the cooperation of Card, director Gavin Hood took on the challenge and the result is an engaging, epic, science fiction film that captures what’s so exciting about the original story while offering up enough visual delights for even the most cynical fan.

The story takes place fifty years after the Formics, an alien bug-like race, attack Earth and kill millions before Mazer Rackham (Ben Kingsley) sacrifices himself in a kamikaze attack on the alien mother ship, thereby saving humanity. In the interim period, Earth has become paranoid, training younger and younger children to fight the aliens, preparing for when the Formics return and again threaten our planet. Ender (Asa Butterfield) is a “third” child, unusual in this future world. Both his older brother Peter (Jimmy Pinchak) and older sister Valentine (Abigail Breslin) have washed out of Battle School, Peter for being too quick to violence and Valentine for being too sympathetic.

Ender is a brilliant and an egotistical tactician who is constantly having to defend himself against bullies. When he does, however, he finds, to his disgust, that he is more like his violent brother Peter and less like his gentle sister than he’d like. One older classmate bullies him and Ender beats him, barely stopping from killing the boy. “It’s not just this fight I want to win, it’s all future fights too.”

That’s the key theme of the film: not whether you win the battle, but how you fight. The gruff and almost humorless Colonel Graff (Harrison Ford) is convinced that against the hated alien race how you fight is irrelevant. It’s whether you win. And win for all time, not just a single battle. Balancing that out is Major Gwen Anderson (Viola Davis), who as psych officer for the Battle School represents the gentle, nurturing approach of Valentine, even as Graff is clearly the adult Peter in spirit.

There are many simulated battles in a large zero gravity enclosure — Battle School is a floating space station above Earth — and while they don’t seem directly relevant to the battle against the Formics, they allow Ender to demonstration his unusual tactical and strategic approach, one that earns him many enemies but just as many admirers as he keeps leading his groups to victory.

The Formics are amassing on their home planet again, however, and in one somewhat confusing scene we learn that they’re only 28-days away from Earth. Another invasion? There’s no time to lose. Except that timeline is never mentioned again and subsequent to that scene Ender refers to “days and days, months and months of simulated battle”, making me wonder what happened to that 28-day deadline?

The computer graphics are terrific in ‘Ender’s Game’ and the final simulated battles on the Formic home planet are far better than the rather mild wire-work combat simulations earlier in the film. We’ve become accustomed to good visuals in science fiction epics like the technically impressive ‘Gravity’, but I couldn’t help think how far we’ve come from the floating space station in ‘2001: A Space Odyssey’ when we first head towards the Battle School in ‘Ender’s Game’.

The greatest weakness in the film, however, is the acting. Asa does a credible job as Ender, though there were a few points where I’d have liked to see more emotion rather than his alternating stoic and tear-filled eyes, but the weak link is the usually quite likable Abigail Breslin. There’s a critical scene on Earth when she (Valentine) must convince Ender to go back to Battle School to help save humanity, and the entire scene needed to have been reshot. When you see the movie you’ll know exactly what I mean. Both actors needed to emote, but instead it’s flat, so flat that it’s hard to imagine how she could have convinced him to row their raft back to shore, let alone go back into space.

Still, ‘Ender’s Game’ is a film well worth seeing even with these weaknesses. The story offers a profound exploration of the morality of battle, killing and genocide through both Graff’s manipulation of Ender and Ender’s own experience and reaction to the climactic simulated battle. And while the film is cast somewhat as a teen adventure in the vein of ‘The Hunger Games’ or ‘Harry Potter’, there’s much to enjoy in this sci-fi epic coming of age tale.