In a sci-fi world of the future, some evolved ant-like Beings left their homeworld to establish a colony on a suitable planet in another solar system. That world was Earth and it was occupied. After a war, they retreated.
The Earthlings felt threatened and decided to fight the invaders (the only intelligent beings they had ever met). To that end, they trained and tested all sorts of young humans, seeking the best natural war-generals. To make a long story short, they eventually found a youth with unusual strategic and tactical skills.
His name was Ender. He succeeded at the military games in the academy by unusual tactics. Slowly he learned strategic skills. But he had odd dreams of the Enemy.
After successes at the academy, he was brought to the advanced training center where he was challenged in harder ways, but always succeeding.
I know the story from the book, but I saw it as a movie a few nights ago. Movies seldom present the nuances of a book, but this one did at least a B grade.
In the book, Ender advanced slowly through all the training sessions successfully until the end. The Enemy was not much presented or understood. In the movie, the Enemy was often shown and even explained.
In both, Ender is presented with increasingly more complex battles until the Government is convinced he can be a Battle-General.
In the book and in the movie, there are points where the reader/viewer can see the truth of the situation. But there is a difference. In the book, the moment of truth sneaks up very gradually. In the movie, it is pretty obvious.
I remember reading the book. There is one spot where you suddenly, horrifyingly, realize that Ender (without his knowledge, thinking he is engaged in just another training simulation) destroys the Enemy completely and utterly. He destroys an alien race not knowing that his "battle" is real. And you, the reader, know before he does.
Few stories raise the hairs on my arms and neck; that one did. The sudden understanding that the simulation was reality was a shock. I have only felt that way with one story before (The Star).
They did a reasonable job of it in the movie, but of course nuance is not a movie trait. Ender's discovery that he had destroyed the Enemy in what he thought was a training session was presented a bit too suddenly. The book gave gradual hints; the movie just thrust the fact on you.
But most movies made from books are worse. If the book was an A+, the movie was an A-. Compared to other book-to-movie attempts, that's not bad. Consider either version of Dune, or Howard The Duck, Hitchhiker's Guide To The Galaxy, Alice In Wonderland, and How The Grinch Stole Christmas movies.
I'd watch Ender's Game again.
And BTW, I met Orson Scott Card once before he was famous. He was a speaker at a conference. He had a routine called "The Speaker On The Monitor" (I think) and it was hilarious. It was back in the days of computer greenscreens and was a rif on biblical chapters (no disrespect meant - simply humor). Like he would refer to the god of the computer and make the sign of the monitor (fingers shaping a square). I actually shook his hand afterwards.
I also met Issac Asimov once at a college presentation, but he seemed dead drunk. Not like I could be sure, being a bit high myself at the time. But he was beet red-faced and slurred as he spoke, and he made no sense at all. Meeting famous people sometimes isn't all that good.
So read the book 'Ender's Game' and get the real story.