Writer-director James Gunn’s latest certainly isn’t the first film about ordinary people who decide to become superheroes. At the same time, I feel confident in promising that it’s unlike anything you’ve ever seen. It makes Kick-Ass look like an episode of “Mister Rogers’ Neighborhood.”

Rainn Wilson stars as Frank, a sad-sack burger flipper whose life, we learn early on, has had precisely two high points: marrying his improbably hot wife, Sarah (Liv Tyler), and pointing out a fleeing criminal to a police officer on the street one day. He makes crude, childlike drawings commemorating these events and hangs them up so they’ll be the first things he sees in the morning and “inform” his day.

As it turns out, they inform the entire movie. When Sarah runs off with Jacques, a local drug lord played by a never-funnier Kevin Bacon, Frank’s life is momentarily drained of meaning. A recovering addict, Sarah apparently was drawn to Wilson’s character by his normalcy, only to overdose on the tedium of suburban life with a fry cook.

Frank doesn’t remain normal for long. After lonely weeks of watching a Christian cable channel and coming to a slow psychological boil, he begins to believe God is communicating with him through a low-budget show featuring a Satan-battling superhero. Then, in a scene so nutty it could turn David Lynch green with envy, he experiences what he interprets as divine intervention. That’s all it takes to get him into a homemade costume and a new career of fighting crime.

Reborn as the Crimson Bolt, Frank doesn’t hit his stride right away. First come highly comical sequences in which he waits in vain behind Dumpsters for something nefarious to happen. In time, it occurs to him to visit the library and ask the woman at the reference desk where most of the town’s illegal activity takes place. She Googles the name of the street where the most drug arrests are made, and, the next thing you know, incredulous thugs are finding themselves tackled mid-deal by some dork in a tight red outfit.

Several embarrassing thrashings later, it hits Frank that he needs a signature weapon. He visits a comic-book shop and asks the sales clerk (Ellen Page) to show him comics about crime fighters who don’t possess actual superpowers.

Soon bad guys (and, in some cases, merely rude guys) are tasting the wrath of the Crimson Bolt’s bright-red pipe wrench. Reports about the vigilante start appearing on TV, Page’s character puts two and two together, and Frank finds himself with an adoring — and sexually aggressive — “kid sidekick” by the name of Boltie.

Gunn has an extraordinarily clever way of keeping the viewer off balance by switching among tones and genres, messing with expectations. Super starts out like an indie about a small-town slacker — a film we’ve seen a hundred times — and shape-shifts from quirky character study to black comedy to exploitation flick to cockeyed romance to ultraviolent revenge drama and, finally, to something so far out of left field it would be criminal even to hint at it. The movie contains moments of soaring hilarity back to back with developments as dark as those of the heaviest Hollywood dramas.

It’s a riveting cinematic experiment, certain to offend as many as it impresses. I found Wilson and Page brilliant in the way they initially play types for which they’re well known and, without warning, give them bizarro tweaks, as if pulling an ace out of a sleeve. Speaking of surprises, who would ever have expected filmmaking this challenging and adventurous from the mind behind 2002’s Scooby-Doo?

This is a picture bristling with originality. How often does such a creation come along? In a season of been-there-done-that sequels, remakes and kiddie fare that underwelms in three dimensions all at once, movie lovers have reason to celebrate: Super has come to the rescue.