When I (definitely) read Ender's Game as a kid, I probably thought it was a cool story about a kid getting good at war training, military moves, and strategy.
As an adult, this is what the novel starts to manifest as.
As an adult, this is definitely not what the novel is. Instead, it is a commentary about control. Control over relationships, control over people, control for the sake of control.
Ender's Game is a tale about, Ender, Peter and Valentine, three siblings. The fact that they're siblings at all is nothing short of the result of a governing force that allows their parents to have a third child, because, well; they need it for the war effort.
The war effort? Against "The Buggers!", of course, an indistinct, rarely described alien species that had their "invasion" attempt stopped at Saturn. Now, humanity waits for the next wave of an attack from an unknown force, and Ender is whisked off to a space station where he trains to become a soldier.
He has potential, he has strategy, but he also has emotions, a trait not very much desired in such mechanical human force. He's also the youngest boy there. He's also quiet, diligent, and ever so cunning.
As the story continues, it becomes densely packed with conspiracy.
I won't be saying anything else about the story but instead talk more about the themes in general.
The most uncomfortable of these is the remove of Ender's ability to make choices about his own fate. Without any agency, he is a vulnerable, broken character who many people can find meaning in, for it is easy to remember times where your ability to control the outcome of a situation was taken away, much to your own protest.
Ender's game is a book that plays tricks on you as you read it. While it won't make a coin appear behind your ear, or pull a rabbit out of a hat, it misleads you.
What starts as a story about a war for human survival turns into a story about absolute control. A story about traumatic events, and of pushing people to their breaking points, tangling their puppet-like strings until they can't take it anymore.
It hits with this meaning much more potently as an adult reader, and reminds us that we need to treat other people with compassion.
Now, there was a movie of this, but I haven't seen it. I won't see it. The book was concerning enough.