The siblings in Zathura aren’t quite as fond of each other as the Bennett sisters are. Danny, the youngest at 6 and three-quarters, laments that he’s not as good as his older brother at such things as playing catch. Walter, 10, agrees that Danny sucks in general, and constantly antagonizes him by calling him a baby. Teenage Lisa, meanwhile, prefers to ignore both brothers, sleeping into the afternoon with headphones on even when Dad asks her to watch them. Ultimately, though, this is a story about love—with robots, reptilian monsters, and unfriendly spaceships that try to shoot the kids’ home into oblivion.

Zathura is author/illustrator Chris Van Allsburg’s third book to be adapted to film, after 1995’s cool but slight Jumanji and last year’s disastrous Polar Express. Mercifully, Zathura’s big-screen version is closer to the former. The story, adapted by John Kamps and War of the Worlds scripter David Koepp, is pretty similar to Jumanji’s: After the kids’ father (Tim Robbins) steps out for a while, Danny (Jonah Bobo) finds a weird game in the basement of Dad’s creaky post-divorce home. He winds his discovery up with a key and then presses a red button, which spins a counter and makes a tiny spaceship move the corresponding number of steps on the board’s swirly path. Also, a card pops out of a slot. “Meteor shower, take evasive action,” it reads. Walter (Josh Hutcherson) turns away from the TV just long enough to tell Danny what “evasive” means before fiery meteors start destroying the living room.

The onslaught, orchestrated with frightening intensity by director Jon Favreau, isn’t the only problem the boys have: When they open the front door, they discover they’re out in space. Frantic pleas for help from Lisa (Kristen Stewart) are dismissed, and the next spin of the game’s dial freezes both Sis and the upstairs bathroom as she’s making her way to the shower. When a card pops out saying, “You are visited by Zorgons,” you know it’s not going to be good.

And so Zathura goes, with each turn the boys take resulting in another development, from a giant robot whose faulty programming makes him try to kill Walter to a lost astronaut (Punk’d’s Dax Shepard) seeking refuge in their floating house. This relay of predicaments keeps the film’s 101 minutes moving briskly, and with enough imaginative whiz-bang to entertain even the grown-ups in the audience. (It’s definite PG material, though, meaning all but the steeliest small children will probably be, well, too traumatized to drag out Chutes and Ladders ever again.) And excepting an unconvincing sequence in which the house is turned on its side, Zathura is aces visually, decorated with colorful planets and fireballs so brilliant it’s almost a disappointment when things stop being blown up.

Though the morals about broken homes, being different, and appreciating your family are delivered rather ham-handedly—“Walter, there are some games you can’t play alone,” the astronaut tells him—the script is frequently sharp and funny. Shepard’s visitor, when not spouting Hallmarkian treacle, is especially entertaining as the sarcastic adult who takes the game as seriously as the boys do, and the older kids get to be smartasses, too. (When Dad asks Lisa not to describe dates as “hooking up,” she whines, “God! We never should have rented Thirteen!”) Little Danny, not quite ready to embrace his siblings’ pissiness but slowly catching on, gets occasional laughs from his cute insistence that he’s not a baby, such as when he declares a card that actually says, “Rescue stranded astronaut” reads, “Rest on standing Astroturf.” All three young actors are suitably bratty and completely believable as sparring siblings. If you recently made your kids sit through The Adventures of Sharkboy and Lavagirl in 3-D, here’s how to make it up to them.