Here’s the super-short version of Ender’s Game: Ender is confronted with an opponent whom he cannot beat…and then Ender beats that opponent. And then Ender feels bad about it. Wash, rinse, repeat. (For an alternative super-short version, check out this one.)
Here’s a slightly longer version: Ender Wiggin beats up a school bully named Stilson, which makes the military recruiters decide that Ender is the one they need to command the army against the aliens, called the buggers. (No, don’t go beat anyone up when you want leadership roles, please. This is an isolated case.)
Ender’s family life is… complicated, since his sister Valentine wants to protect him and his brother Peter wants to kill him. But no worries, because Colonel Hyrum Graff is here to whisk Ender away to the most awesome destination after Disney World: Battle School. On the way to Battle School, Ender runs into another bully named Bernard, and Ender beats him up also (both physically and socially, by spreading rumors about the kid).
At Battle School – in space! – Ender excels because he understands that there’s no up or down in space. Also because he’s just smarter than everyone, even the older kids.
Ender is lonely, but eventually becomes friends with some kids, notably Alai. Then, after he makes friends with some other new kids, Ender gets transferred to Salamander Army, where he has zero friends. Ender’s commander Bonzo dislikes him, which doesn’t help that situation. But Ender also meets a girl named Petra, who teaches him how to shoot for the zero-gravity laser tag game that is the entire focus of the school. (Imagine Harry Potter’s Hogwarts if Quidditch were the center of the school. Oh wait, it kind of is.) Ender practices the game and soon gets transferred to Rat Army. There he meets Dink Meeker, who reminds him that the game is just a game and that adults are just lying jerks.
Back on Earth, Peter and Valentine Wiggin are taking over the world by – and we’re totally serious about this – posting political opinions online. The classic rebuttal to that plan is this comic.
Meanwhile – in space! – Ender is given his own army for the laser tag game, and you know it’s going to be a good army because it’s named Dragon Army. (Seriously: can a dragon beat a rat? What about a salamander? Yes, of course.) And – surprise, surprise – Ender wins over and over with Dragon Army, even against unfair odds. Ender even beats his old commander, Bonzo. So Bonzo tries to kill Ender. But Ender beats up Bonzo and feels bad about it.
Colonel Graff takes Ender to Command School. We also find out that Ender has killed both Stilson and Bonzo, though Ender doesn’t learn this until later. At Command School, Ender meets Mazer Rackham, hero of the second bugger invasion. Mazer sets Ender up with a new computer simulation, and this time Ender has his old Battle School friends acting as sub-commanders under him. They play the simulation and win the game. But it turns out to be a real war. Oh no. So Ender has killed the buggers in a very dramatic act of genocide. Or “xenocide,” the killing of something foreign. Or maybe geno-xeno-cide? Or maybe self-defense? Whatever you want to call it, Ender feels really bad about it.
Valentine convinces Ender to go out to a new colony with her. There, Ender discovers that the buggers left him a message to say that everything’s cool, even though he, you know, kind of killed them all off. Except he didn’t. The buggers left him a bugger pupa in a cocoon so that he can restart the bugger species.
Which is a nice way to move us towards the sequel where, we’re just guessing, Ender probably feels bad about stuff.