Only two weeks into ABC’s new plane-crash-survivors-on-a-tropical-island thriller “Lost” and already the mysteries are flying fast and furious. Are the castaways alone? Is that really a polar bear? And what’s that huge, growling thing in the jungle, flattening trees and sending the island’s new residents scrambling in terror?

Yet the most intriguing mystery is less about the adventure and more about the people watching it unfold: How has “Lost” attracted such a huge audience? Nearly 18 million viewers found the Sept. 22 premiere - making it ABC’s most-watched drama debut in nine years. The ratings for the second installment weren’t as sky-high as the highly hyped premiere, but the still impressive numbers (16.3 million viewers) suggest that the initial spike in viewership was no fluke.

Scoring big - or, let’s be frank. even respectable - ratings has traditionally been an uphill struggle for a show like “Lost,” the latest offering from J.J. Abrams, creator of “Alias” and “Felicity.” Genre-bending TV - programs that combine several hallmark elements from distinct styles of shows - is more often than not relegated to cult status, pulling in a tiny but enthusiastic audience.

Most cult shows are all but ignored by mainstream America, who’d rather while away the hours with tepid fare like “America’s Next Top Accountant” or “Last Pork Roast Standing.” “Buffy the Vampire Slayer” and “Angel,” for instance, were extremely well-crafted horror-comedy-drama-thrillers - and attracted a middling viewership in only the single-digit millions each week.

So what’s “Lost” got that other hyphenated (and now cancelled) shows didn’t? If the number of billboards and bus placards is any indication, it’s got the support of its network behind it. More importantly, it’s got several buzzworthy elements designed to appeal to a large number of people - and get them talking. In fact, “Lost’s” first episode actually added viewers as the show went on, indicating that phones and computers were busy with word-of-mouth suggestions to “Turn to ABC. You’ve gotta see this show!”

Genre-bending thriller Ostensibly, “Lost” is about 48 plane crash survivors fighting to stay alive on a tropical island, a basic premise which has been done again and again, from “Robinson Crusoe” to “Lord of the Flies” to the exploits of a certain skipper and his little buddy. But it’s already shaking out to be much more than a “Gilligan’s Island” retread. Viewers of the show’s initial hours already know that “Lost” is a competent, high-concept thriller. But it’s also a character-driven drama, a compelling mystery, and maybe even - stay tuned - a sci-fi adventure.

And that’s the beauty of “Lost.” It’s made up of seemingly dissimilar elements that each appeal to a specific audience. And the sum of its parts is all the more impressive.

It’s tough to be all things to all people. But “Lost” seems to be enough things to enough viewers to draw in plentiful, if disparate, audiences, each looking for something particular out of the show. From cheesecake and beefcake - good-looking people showing plenty of skin in a tropical setting - to harrowing disaster scenes, tense suspense and smart comic relief, “Lost” is delivering the goods. Something about it is familiar enough to attract mainstream viewers. And it’s unique enough to give fans of genre shows plenty to chew on.

Sure, “Gilligan’s Island” employed many of the same basic plot elements. But I’m confident enough in Abrams to know that a group of robots isn’t going to challenge the Harlem Globetrotters to a basketball game anytime soon. But, who knows? Just when viewers think they’ve got “Lost” figured out, it zigs, then zags, then zigs again. It’s “Jurassic Park” one minute, “Gosford Park” the next. If television has taught us anything, it’s not to pigeonhole J.J. Abrams.

His “Felicity” started as a girl-moving-to-the-big-city show, and ended as a time-traveling fantasy (seriously). “Alias” is at its core a globetrotting spy procedural. But it’s also a science thriller that beats the pants off anything Michael Crichton has come up with recently, as well as an is-it-or-isn’t-it-sci-fi-meets-historical-prophecy-techno-jumble that would have “Da Vinci Code” author Dan Brown scratching his head.

So maybe a coconut phone or bamboo jet pack is indeed in “Lost’s” future. With Abrams, you never know. And that’s part of the fun.

Characters to care about Still, all the rollercoaster plots in the world aren’t going to amount to much if the characters riding them aren’t worth worrying about. While Abrams can craft multifaceted characters, much of the depth can likely be attributed to another co-executive producer on the show, Damon Lindelof, who co-produced the talkier “Crossing Jordan.” Even without the taut suspense and breathless thrills, the characters on “Lost” stand on their own as interesting people, layered with interesting quirks, questionable motivations and, no doubt, plenty of secrets.

And the acting is on par with the slick writing. Matthew Fox (“Party of Five”) delivers a sympathetic-yet-heroic turn as a beleaguered doctor who finds himself in the middle of this nightmare. Newcomer Evangeline Lilly is a likable and levelheaded woman who’s harboring at least one big secret. Former hobbit Dominic Monaghan plays a helpful-yet-shifty musician who was up to something when the plane crashed. And nearly a dozen other characters, many of them familiar TV faces, play roles of varying importance. On the surface, anyway. It’s plainly clear that a bit player now could become integral to the plot as the series continues.

But don’t get too comfortable with these specific castaways. Abrams has killed off major characters before. What’s especially intriguing about “Lost” is that if some, or all, of the original bunch of lead castaways are rescued - or picked off by the hungry thing in the woods, there are three dozen other characters hanging out on the beach, just waiting for their time in the spotlight.

Is this finally a horror-sci-fi-suspense-thriller that Great-Aunt Marge can feel comfortable admitting that she watches? Early returns say yes indeed. Abrams has disregarded the traditional rules of these standard genres, deconstructed them, then reassembled them into something wholly new and appealing.

Of course, we still don’t know what’s lurking amid the foliage or many of the other surprises the show has yet to unleash. But no matter what the producers have planned, it seems that they’ve already learned how to dress up what have typically been dismissed as nerdish elements in normal-people clothes so they appeal to the masses.

It’s still early in the game, but “Lost” apparently knows exactly where it’s headed.