Fiona (Cameron Diaz) sleeps peacefully, but her husband, Shrek (Mike Myers), is troubled, in a scene from Shrek Forever After. (DreamWorks Animation/Paramount Pictures)

All along, the Shrek series has shrewdly played to children as well as their popcorn-buying parents. For the under-10 crowd, there’s a chorus of burps and farts; and for the grown-ups, there’s arch pop culture references and a hipster-friendly soundtrack (the original film included John Cale’s gorgeous version of Leonard Cohen’s Hallelujah).

All along, the Shrek films have played to children as well as their popcorn-buying parents. But in Shrek Forever After, the concept seems tired.

Embedded in the silly anarchy of skewered fairy tales are adult-approved morals about loyalty, commitment and beauty coming from within. So far, it’s been a win-win, blockbuster formula: plenty of gross-out gags for the kiddies, a smidge of substance for their folks.

But in Shrek Forever After, the fourth and final adventure of the trumpet-eared ogre (voiced as always by Mike Myers with a Scottish brogue), franchise fatigue has set in. Nowhere is this more apparent than in the swamp where Shrek and Fiona (Cameron Diaz) have set up housekeeping with their baby triplets. Each day is the same grind of domestic chores, diaper changes and fending off throngs of tourists who want a snapshot of their hero. Even Shrek’s soothing nightly martini (garnished with an eyeball) is interrupted by the demands of family life and drop-ins by sidekicks Donkey (Eddie Murphy) and Puss in Boots (Antonio Banderas).

Before long, Shrek is wallowing in a midlife funk. He’s a monster emasculated by marriage and fatherhood. But who wants to watch a flatulent ogre kvetch about lost opportunities and wonder where his passion went, like some big green Greenberg? All that monotony gets monotonous until Shrek blows his stack at his childrens’ first birthday party, smashing a cake and storming out to sulk in the forest.

The fun finally starts when Shrek meets Rumpelstiltskin (Walt Dohrn), a pint-sized conniver, who nearly became the king of Far Far Away when Fiona’s parents asked him to break her curse. But before that could happen, Shrek and Fiona fell in love, thwarting Rumpelstiltskin’s evil plans.

Rumpelstiltskin (Walt Dohrn, right) is Shrek's foe in Shrek Forever After. (DreamWorks Animation/Paramount Pictures)

So when Shrek stomps into Rumpel’s path, the little man sets a trap. He concocts a deal that gives Shrek a day of freedom – with all the villagers he can terrify and all the mud he can rut in. The ogre agrees, but doesn’t check the fine print: in the alternative kingdom where Shrek lands, Rumpel is the sleazy dictator of Far Far Away. Donkey is in the service of wicked witches and Fiona is the leader of an ogre resistance movement. This is what the world would have been like if Shrek had never been born.

Like George Bailey, Shrek discovers that his previous dull existence was, in fact, a wonderful life, and he spends the rest of the movie trying to get it back. All the usual Shrek shtick is in play: Murphy’s maniacally goofy Donkey and Banderas’s preening Puss steal every scene they’re in. Though in the alternative universe of Forever Ever, Puss isn’t a swashbuckler, but a plump and pampered house kitty who’s lost his mojo.

Even more interesting is Fiona’s girl-power turn as a warrior princess — she’s now drawn like an underground comix heroine. In this world, she didn’t wait around for a magical kiss, but instead rescued herself. And while many of the guest voices are underused – Kathy Griffin and Jane Lynch have barely-there appearances – dreamboat du jour Jon Hamm has been slyly cast as a buff ogre.

Still, there’s little that’s novel in Forever After. The self-referential pop culture riffs now feel like a snake eating its own tail. Everything in the film is recycled – from the Capra storyline to the ironic dance numbers. The 3-D effects add some oomph to a palace battle scene, but otherwise nothing pops – the dead-eyed computer animation actually looks muddier in 3-D.

It seems like Shrek isn’t the only one suffering from a mid-life slump. In its attempt to cash in once again on a beloved character, the franchise looks as desperate as a bald guy with a ponytail.

Shrek Forever After opens on May 21.

Rachel Giese is a writer based in Toronto.