Jonah Bobo stars in Zathura, which can best be described as Jumanji in space.

LOS ANGELES -- By his own reckoning, at 39, Jon Favreau is too old to "swing." So cue the second childhood.

"I'm not the new, edgy guy anymore," says Favreau, who made his name nine years ago writing and producing Swingers. It was a snapshot movie of the then-hip "New Lounge" scene, starring him and his pal, a fellow unknown named Vince Vaughn.

"Having kids makes your whole frame of reference change," he says. "If you look at Made (directed by Favreau, again co-starring him and Vaughn), it was the last movie I made before I had kids. It's a strong 'R,' there was violence in it, a lot of cursing."

And now? He has two kids (4-year-old Max and 2-year-old Madelaine)and two kids' movies under his directorial belt -- the Will Ferrell hit Elf and the soon-to-be-released fantastical space adventure Zathura, the latest taken from the evocative books of children's author Chris Van Allsburg (Jumanji, The Polar Express).

Literally "Jumanji in space," the book involves two battling brothers, Walter and Danny, who find a magical space-adventure board game that sends their house hurtling somewhere past Saturn, there to be assailed by meteors, a murderous rogue robot, and reptilian space pirates called Zorgons. Only by playing the game through to the end are they able to find their way home.

Favreau says one of the attractions was the blank slate he and scriptwriter David Koepp got, by dint of the brevity of Van Allsburg's books -- a rare case of having to add to a story, rather than subtract from, to make it into a movie.

"The style of the book was '50s science fiction, so we made it a '50s tin toy game as opposed to a board game with dice," Favreau says. "It became about doing sci-fi in the style from when I was growing up.

"The biggest departure we took from the way these movies are done now is we shot the spaceships in the way they would have in the old Star Wars movies as opposed to the new ones. We built miniatures and did motion control and shot it on a miniature stage and cobbled it together, which the the most fun way of doing it -- and when it's over you have things to hang in your house."

Most of it was real -- including the Zorgons and robot, both designed by master monster-builder Stan Winston (Jurassic Park, Aliens). And so was the house, a series of three giant "gimble" sets (a hydraulic device, typically used to represent the cockpit of a plane, but here used to stand in for entire floors of a house).

Thess provided vertiginous thrills for child actors Josh Hutcherson (Walter) and Jonah Bobo (Danny), as well as Kristen Stewart (teenage sister Lisa) and Punk'd's Dax Shepard, who plays an astronaut they befriend.

"Here we're building the whole floor of a house," Favreau says, "and that (gimble) was intimidating when you saw it move. When it went from level to 30 degrees in what seemed like a second, and you're on board and riding it and screwing yourself in, literally bolting the camera to the floor ... well, let me tell you, when you're on a floor and it tilts even 10 degrees, you're off your feet. If it goes to 30, you feel like you're on the Titanic."

Add actual pyro and explosive charges to recreate the meteor showers and Zorgon space-cannon attacks, and you have a set that is definitely not designed to last.

"It's a director's dream to shoot a movie in (chronological) order, and we actually had to do that," Favreau says. "The excuse was the house comes apart over the course of the movie. And the kids were going to change, too, over the course of the months we were shooting."

Now an old hand at directing children, he says having physical representations of aliens, robots and explosions brought better performances out of them.

"When people say kids have good imaginations, it's true. But they're terrible liars, and acting is more like lying than it is imagining. You tell them this greenscreen is really a robot, you get a terrible performance.

"As a director I talk them through how they feel, bring them up to speed with what scene they're in. And then if you have a real guy in a suit, they're going to react honestly to that. If we have a game where the pieces really are moving and cards are popping out and Jonah is seeing it for the first time, his eyes sort of light up.

"I think some of the best stuff in the movie is closeup work of a seven-year-old reacting to something for the first time. It's a wonderful thing if you can do it. It takes a lot of trouble to make a whole set shake or tilt, but if you can safely put the kid in that environment and have walls blowing up and glass shattering and he can experience that, you see him jump and shake and move and flinch in ways he can't do consciously."

Although there are shortcuts. For some scenes Favreau admits he used an airhorn to elicit shock from the kid. "But that ran out of steam fast," he says, chuckling.

Still an occasional actor, Favreau had a small role and a reunion in Chicago recently with Vaughn, who filmed the ironically titled The Break Up with Jennifer Aniston.

"Chicago is where he's from and where I Iived for four years. So it was great to go back there, we felt like royalty. Vince always finds the time to go out, and it's fun, but I'm on the other shift, the morning shift these days."