It’s hard to knock this game show

I’m not an easy sell when it comes to quiz shows, especially of the steroidal variety that has colonized prime time over the last decade or so. The mothership lighting, the Armageddon noises -- so much false fire, so little substance.

But there is nothing I don’t like about “Opportunity Knocks,” which begins tonight on ABC and which might take as its motto, “The family that stays together, plays together.” As a celebration of ordinary folks, it forgoes the aggressive bathos of its stablemate “Extreme Makeover: Home Edition” in favor of a tapestry of happy details, including the sounds and smells of family life. It is sweet and delightful and, although I really hesitate to use this word to describe anything from the famous pixie-dust factory that owns the network, really sort of “magical.”

The contest consists of family members answering questions about one another to win money and prizes, which is straightforward enough and entertaining on its own. But what makes it work so well, I am surprised to say, is the Big Gimmick: the fact that the show is staged on the contestants’ front lawn.

This is accomplished by the arrival of a fleet of semis and the staff necessary to convert a suburban street into an open-air television studio. The charm of “Opportunity Knocks” has something to do with the fact that it takes place outside at night, in a (comparatively) natural setting: Tonight’s episode takes place beneath a canopy of trees. It’s almost a fairyland effect, like a carnival come to town.

Actor-impresario Ashton Kutcher, of “Punk’d” and “Beauty and the Geek,” is one of the executive producers, alongside host J.D. Roth, whose own career encompasses both the light and dark of reality television (“The Biggest Loser” on the one hand, “Breaking Bonaduce” on the other). Roth has hosted game shows for kids and adults alike, and he’s easy with his guests, friendly and informed, but not over-familiar.

Kutcher notwithstanding, the show is not a prank. It’s not as if Roth and company sweep in out of nowhere. You have to apply to be on the thing. Research is done, questions written, accomplices briefed, prizes devised to fit the needs and dreams of the contestants. In tonight’s episode, which features the Gutierrez family from Torrance, these include a 1969 Camaro for dad Walter and backstage passes to a Jonas Brothers concert for daughter Alexis. (The JoBros are, not coincidentally, under contract to ABC corporate parent Disney; next week the show will cross-promote the Disney Channel’s “Hannah Montana.” It’s the only thing about “Opportunity Knocks” I found bothersome, but I am admittedly more sensitive to these things than the average viewer.)

With an audience of friends and neighbors, the show is infused with a marvelous sense of occasion. “I’m so excited,” son Lucas tells Roth. “This is like a dream.”

He’s called on to tell by scent the hair gel his older brother uses; to pick his father’s favorite toy car from the 300 stashed beneath his bed; to recognize his sister’s award-winning cheerleading move. Mom Patty has to guess her husband’s weight, correctly pick which of four remarkably similar drawings was done by her older son (not a contestant) and shred the rest.

Sister has to identify the bark of the family dog and guess which of her friends her brother has a crush on. It can be embarrassing, but in a nice way.

I watched the whole thing with a big stupid smile on my face. That’s really the best critique I can offer.

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robert.lloyd@latimes.com

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‘Opportunity Knocks’

Where: ABC

When: 8 tonight

Rating: TV-PG (may be unsuitable for young children)