Twenty years ago tonight, FOX debuted a strange little show called "The X-Files." Its stars were virtually unknown — Gillian Anderson was only 24 when the pilot was filmed, and if you recognized David Duchovny at all, it was either as the cross-dressing FBI agent from "Twin Peaks" season 2 or as the man who read letters at the start of every episode of "Red Shoe Diaries" — and the format was an odd mash-up of science-fiction and police procedural, as FBI partners Mulder (the believer) and Scully (the skeptic) traveled the country investigating reports of paranormal activity.

FOX put it on Fridays, which in 1993 wasn't the network wasteland it is today, but was still not the place you schedule anything with high hopes for. But within a few years, "X-Files" became one of FOX's biggest hits (it would eventually move to Sundays), popular enough to launch a feature film spin-off midway through its run (and another a few years after the TV show ended) and run longer (nine seasons) than any American primetime sci-fi series before it.

"The X-Files" would be one of the most influential drama series of all time, not just because of the talent working behind the scenes — including a young Vince Gilligan and Howard Gordon — but because of the concepts it introduced into the consciousness of both the audience and the shows that followed it. "X-Files" introduced, for good or for ill, the idea of a series having a "mythology" — a complicated backstory and ongoing story arc that would take years to play out, and be explained — and the show's creator, Chris Carter, set up a clever structure to deal with it. Most episodes would be standalones in which Mulder and Scully dealt with some Monster of the Week — the Flukeman, a shape-changer (both of them played by the series' most imaginative, and reclusive, writer, Darin Morgan), a teenage boy with lightning powers — but every now and then, Carter would roll out an episode that was wall-to-wall mythology, featuring hints about the disappearance of Mulder's sister, the agenda of the mysterious Cigarette-Smoking Man, black oil, informants named Deep Throat and X, etc. Carter swore he had the mythology all mapped out, and so the audience signed up for the long haul to find out what the aliens were up to, enjoying the weekly monsters in the meantime.

Carter also Trojan Horsed the sci-fi elements inside the more familiar cop show elements, making "X-Files" the rare nerd show that felt acceptable for non-nerds to watch and obsess over.

You can see obvious "X-Files" DNA in shows its alums have created or worked on ("Breaking Bad," "24," "Homeland") and on other popular shows whose creators were obviously fans (most of J.J. Abrams' shows — "Lost" and "Fringe" especially — owe an enormous debt to "X-Files"). These shows have also come of age in a post-"X-Files" world, which meant they could follow the successes of that show (would "Lost" have been such a huge hit out of the gate if viewers had known there would be time-travel, telekinesis and other sci-fi weirdness?) while also trying to avoid its pitfalls.

At the time "X-Files" aired, it was most celebrated for the mythology. We only got a handful of those episodes a season, especially in the early going, but even more than the monster episodes, they felt new and exciting and the thing to talk about. The problem was, they amounted to very little in the end. Some of the show's writers have insisted that Carter really did have the mythology mapped out in the early days, and that the success of the series — and the desire to make a movie (which at one point was going to be the conclusion to the mythology, until someone decided that this would kill the TV show) — forced him to elongate it until it became gibberish. In his basement office, Mulder had a poster that said "I Want To Believe," and the audience was right there with him until they realized there was nothing to believe in.

In hindsight, what holds up about "X-Files" isn't the mythology, but the monsters. The standalone episodes that were considered at the time the cost of doing business hold up — some of them spectacularly well, like Darin Morgan's comic masterpieces "Clyde Bruckman's Repose" and "Jose Chung's From Outer Space," the incest-tastic Glen Morgan/James Wong episode "Home" (I remain to this day amazed that it aired on network TV) and Gilligan's "Drive," the episode that years later would lead to Bryan Cranston playing Walter White.

The dream of nearly every sci-fi series since has been to find that perfect "X-Files" balance of episodic and serialized storytelling, and of elements that will appeal to nerds and non-nerds alike.

"Lost" pulled it off for a long time, but eventually shrunk down to a smaller core audience that didn't object to time travel, resurrection or ghosts in the jungle. "Fringe" unapologetically tried to copy "The X-Files" structure, but their Monster of the Week episodes weren't in the same league as the best "X-Files" ones, and the audience seemed impatient to get back to the mythology. That show got much better when it become a pure serial, but ratings plummeted, and it hung around for five seasons largely on FOX's charity.

Twenty years later, the audience is different. They're more skeptical of mythology, feeling burned to various degrees by "X-Files," "Lost" and "Battlestar Galactica." The hardcore fans of these shows tend to prefer serialization, and the more casual viewers who pushed "X-Files" from cult hit to crossover success are busy watching three dozen other things. ("X-Files" had the good fortune to debut at a time when home entertainment options were far more limited.)

It's hard to imagine a show like "X-Files" becoming a massive hit today. "Fringe" tried awfully hard, but wasn't as good and arrived in a very different era. Maybe a show with this exact Murderers' Row writing staff, with the perfect deadpan chemistry between Duchovny and Anderson, could zoom to the top of a Best Show You're Not Watching list, or bring some shine to a once-obscure cable channel, or become a solid but unspectacular success for a broadcaster. But would it be a top 15 show at its peak, spawn an expensive feature film and work its DNA into shows for the next 20 years? Probably not. Right show, right place, right time.

What does everybody else think? Do you think if you could bend reality so that this exact show (give or take the cell phone technology) debuted in 2013, would it be a hit? What are some of your favorite episodes? Did the resolution of the mythology (or lack thereof) sour you on the show to the point where you don't revisit it anymore?

Alan Sepinwall may be reached at sepinwall@hitfix.com