Ender's Game by Orson Scott Card is incredibly enjoyable science fiction.
But why? What makes it so enjoyable? Let's explore.
Ender's Game contains multiple elements that have always been considered critical for great literature to possess. Just as the pleasure of a play is knowing how it will end, the audience likes coming across familiar elements in stories.
Ubi Sunt - Where are they?
"Look on my Works, ye Mighty, and despair!" - from Ozymandias by Percy Shelley
The buggers in Ender's Game are devastated by humans, creating a lost race, an empty world with nothing left in it. Like architecture, the civilizations that world builders create in novels should have high ruin value. People like to look upon and think about what once was something.
The Bildungs Roman, or, the Novel of Development
Almost every one of the best selling books / most read books of all time are in the bildung category. Why? People identify with development--we've all been there.
Learning about what people do with power is never as interesting as either learning how people came to power / developed their abilities or learning how people lost their status. Comedy is roughly the story of gaining status and Tragedy losing it.
Ender Wiggins, we learn, is incredibly gifted, but his move toward leadership isn't a given. He experiences multiple setbacks in his journey. All the better. People rarely like reading stories where everything comes easy.
Conflict -- i.e. Rising Action, Falling Action, Climax, etc.
We like reading about conflict. This is why Cinderella and Sleeping Beauty are told and retold. We also like stories where conflict gets resolved neatly by the end of the story. This is also why Cinderella and Sleeping Beauty are told and retold and, of course, why Ender's Game is so beloved. Kurt Vonnegut noted that Cinderella constitutes a specific narrative arc: things are bad, they get better, they get worse than ever, they end better than ever. Any story where the hero goes through changes in fortune grabs the reader's interest.
Updating the Archetypal Hero
In some ways, we don't really want a new story. We want another version of the archetypal hero myths. Update Odysseus for the 20th and 21st centuries and you have a hero people want to hear about. Ender fits the Odysseus story somewhat. The hero leaves his home, including the people he loves best. He must leave to protect hearth & home. He does protect the home. But when he returns home, nothing is the same. It can't be. Not only has the home changed--so too has the hero.
This story worked so well, Orson Scott Card created a huge series of books that rehashes the tale everyone loved and he even retold the book almost verbatim as Ender's Shadow. Did I enjoy Ender's Shadow? Of course! I enjoyed it because it, by mirroring Ender's Game, the new book again mirrored multiple elements of great literature. Card might as well write a book called The Shadow of Ender's Shadow. As long as it followed the script, we'd all like that one too.
Escape from New York by John Carpenter