Here’s a truth about science fiction and fantasy fans, myself sometimes included: Even though our beloved genres are purportedly “forward-thinking” and/or “open to flights of limitless imagination,” the majority of these fans–these passionately vocal fan boys and fan girls–tend, like most other human beings, to gravitate toward the familiar, to what they know best and feel most comfortable with.

And, like most other human beings, what we know best and feel most comfortable with are the things imprinted on our minds, tastes, and personalities during our formative, impressionable pre-teen and teen years. In that respect, genre and love of said genre can become yet another form of nostalgia.

This brings us in multiple ways to director Edgar Wright and writers Simon Pegg and Nick Frost’s immensely likable new sci-fi film The World’s End, a movie that (if we’re being charitable) can be said to slyly play off fan-boy nostalgia for not only the events but the beloved genres of their youth. (If we’re being less charitable, we could also say Wright, Pegg, and Frost are themselves fan boys spinning through repeats of the genres they loved as kids.)

Which isn’t to say World’s End isn’t a ton of fun or well-made. Pegg plays Gary King, a 40-something British loser trapped in a life rendered empty and pointless by his belief that things were never again as great as they were 20-some years ago when he and his late-teen pals celebrated their last night of secondary school with a 12-point pub crawl (sadly, in Gary’s eyes, abandoned after the ninth pub and pint). The last stop on the legendary list was to have been the appropriately named “The World’s End.”

Skinny and strained, bug-eyed and beaten down by the realities of adulthood (as well as whatever steady stream of substances he uses to numb them), Gary has never truly left the summer of 1990. Bittersweetly stuck in his romanticized past, he’s baffled and battered by the larger world and society around him that his much more successful friends have adapted to. But Gary desperately believes if he can reconvene his old school chums (including Frost, Paddy Considine, Eddie Marsan, and Martin Freeman) to return to their hometown and repeat—and this time finish—their once-epic night out, he will somehow regain the elusive, almost-magical hope, confidence, and potential he felt when he was 18.

The first act of The World’s End is a snappy, funny riff on the dangers of arrested development and chronic nostalgia. It’s the charming, thematic opposite of the classic British coming-of-age story played out with a wit that weaves somewhere between Gervais and Merchant and Abbot and Costello.

But then, as Gary and his reluctant, skeptical pals complete the first third of their revisited pub crawl, the outing and the film begin to veer into the unsettling and odd. Mild Spoiler Alert: It turns out some, perhaps many of the town’s denizens have been replaced by look-alike robots from outer space bent not on invasion but subversive assimilation.

At this point Wright’s much-vaunted genre-blending kicks in. The director made his name with Shawn of the Dead and Hot Fuzz, both of which star Pegg and Frost and both of which use their respective genres (zombie movies and cop flicks) to take playful swipes at the social norms surrounding adulthood, authority, and friendship. Likewise, The World’s End—which completes the film makers’ loose genre trilogy–upshifts into a confidently silly sci-fi action movie, complete with Wright’s trademark mix of inventive (if still a bit tedious) fight scenes and well-chosen soundtrack tunes as Gary et al battle the growing hoards of Invasion of the Body Snatchers-style robots in order to not so much save the world as reach “The World’s End” and complete their epic pint-guzzling quest.

It’s all very clever and very entertaining—almost to a fault. Wright also made the delightfully spastic Scott Pilgrim Vs. The World (another film set to a genre beat about a befuddled, idiosyncratic young man in pitched battle against conformity), and he has a clear and cleverly expressed love for the genres whose trope-y waters he surfs and an admirable devotion to solidly crafted—if sometimes stylistically chaotic—storytelling.

But there are also times when all that dedication to genre leaves The World’s End, like Wright’s other films, feeling “constructed,” existing more as an exercise than a creative expression; as if the film serves the genre, rather than the other way around. As much as I enjoy watching them, I always end up liking Wright’s films more on accrued style and humor (and soundtrack) “points” than as completely effective overall works.

Which brings us back to the notion of fans’ (and film makers’) love of genre as a form of nostalgia. “It never got better than that night—it was supposed to be the start of my life!” Gary hollers at one particularly and surprisingly poignant moment, and you can imagine the film makers are speaking not just of Gary’s stagnant life growth and failures, but of the very genre that has the character surrounded by human-looking robots with glowing Village of the Damned eyes and messy blue goop for “blood.”

Fan boys and girls had been excited for The World’s End for years as the much-ballyhooed conclusion to Wright and Pegg’s Cornetto Trilogy. (So named for the brand of British ice cream that cameos in Shaun of the Dead and Hot Fuzz, and now The World’s End.) Two things genre fans love to do are embrace a film maker (or writer) who speaks their genre to them with love, and then await the film maker’s next work with growing levels of ecstatic, increasingly frenzied anticipation. (What is the annual Grand Geek Ball of Comic Con other than an increasingly artificially managed frenzy of anticipation playing off nostalgia?)

The buzzword “freedom” is often bandied about in The World’s End, usually by way of a Peter Fonda sound clip from Roger Corman’s 1966 The Wild One knockoff, The Wild Angels. The creepy village robot people of course represent, with a big metaphorical bat, the societal conformity one must strive to be free from, but the past 15-year rise of Interweb-fueled geek acceptance and box-office dominance by way of Lord of the Rings and super-hero movies, you can’t help but wonder who’s conforming to what these days.

But while The World’s End lightly explores notions of youth and adulthood and the age-old questions of freedom versus responsibility (as well as the joys of inebriation), its main message is that as comfortingly familiar and reassuring as rose-colored nostalgia for bygone formative days can be, in uncontrolled excess (and if there’s a third thing fan boys and girls do well, it’s uncontrolled excess) the emotion can be crippling, even self-destructive, and ultimately it’s better to move toward the future—even if that future happens to be a post-apocalyptic wasteland. I kind of hope Wright, Pegg, and Frost are aware that lesson also applies to their own adolescent-based love for the horror, action, and sci-fi genres they’ve been successfully playing off.

I love the sci-fi, fantasy, and action genres and appreciate the works of fellow genre aficionados like Wright. But too often fandom—again, myself included–feels stuck obsessing on the genre properties its members loved as youth. Like nostalgia, genre can be a crutch and a cage. To grow and get better, stronger, and, yes, free, you need to eventually kick it aside and see what you can do when loosed from both its comforts and constraints. That goes for both fans and film makers.