Billy Mitchell, center, accepts an award for his Donkey

The knot in your stomach, the sweat in your palms, the breathless worry over the final score – and you’re not even playing, you’re watching.

And you’re not watching “the big game,” but a video game.

Worst of all, you’re watching a movie about a video game.

“The King of Kong: A Fistful of Quarters” is a gripping yarn, an edge-of-your-seat thriller, as well as a mocking insider’s view and a genuine giggle. And while it might be about the world “Donkey Kong” record – who claims to have it, who wants it and what the first guy will do to keep it – it’s really about life, character and how we think of ourselves.

This game of nerves between strutting, laughable “world champ” Billy Mitchell of Hollywood, Fla., and weeping, laughable, never-get-a-break challenger Steve Wiebe (of Redmond, Wash.) is a real no-stakes contest to much of the sentient world. “Classic” video games? “Pac-Man”? “Donkey Kong”? Who cares, right?

This Seth Gordon documentary allows us to think that as it wanders through this arcane arcade universe of dweebs, dorks, freaks and geeks.

There’s the boyishly nerdy thirtysomething Brian Kuh, the self-described “heir apparent” to Mitchell.

There’s Walter Day, the former Iowa arcade owner whose “Twin Galaxies” was and still is the place where “real” records are sanctioned in gaming.

Mitchell himself comes off a long-haired, loud-tie-wearing dolt who has cruised through life with that 1982 score as a source of his celebrity. His dad says, “He’s a winner,” a guy who runs a chicken-wing sauce distributor. We cackle.

But Gordon stacks the deck in his film. Wiebe, the pretender to the throne, is an outsider, a middle-school science teacher who, friends and family tell us, has had his shots at glory – a star athlete, an accomplished musician. But he has always fallen short. He has become a spectacular Donkey Kong player, and we watch and hear hilarious home video of his world-record game (interrupted by a son in need of potty-training assistance).

Mitchell, Day and their cabal, the film suggests, do all in their power to disallow this outsider simply because they don’t know him. Will Mitchell bully the new guy into oblivion? Will Wiebe stand up to this? Gordon briskly sets this up and lets us see just how myopic their misspent youth was. The hardcore players are not stupid. They know the game’s patterns, its technology. But they’re limited.

Mitchell, goofily declaring his own greatness, insists that “nobody” remembers the name of America’s leading World War I fighter ace (Eddie Rickenbacker) because he wasn’t “number one,” and then blunders the number of kills the actual No. 1 tallied. Day describes Mitchell vs. Wiebe as one of history’s “great rivalries,” and can only come up with a cartoon duo (who weren’t actually rivals) to compare them to. Gordon invites us to snicker at these guys. But then, “King of Kong” reaches its showdown and we’re given a visual essay on grace, sportsmanship and nerve. At least one of the players doesn’t have any of those.

Oddly, this movie about an underdog-vs.-top-dog rivalry has its own underdog story. The Florida natives who made “Chasing Dreams: Beyond the Arcade,” which is a much better “classic” video-game history lesson, got their movie into the Sundance Film Festival. “King of Kong,” which only got into the off-Sundance Slamdance Festival, has the wittier, more dramatic story to tell and is the one that made it into theaters.

But the biggest difference between these two equally solid movies about lives of misspent quarters? “King of Kong” makes us care.