It’s not typical that a movie makes history with its trailer, but then again, “Cloverfield” isn’t your typical studio blockbuster.

Last summer, as every geek worth his action figure collection was getting ready to see “Transformers” on opening night, the Motion Picture Association of America was dealing with something unprecedented: a trailer submitted for approval with no title and no advertised cast, consisting solely of grainy digital video footage and a release date: “1.18.08.”

By the end of the weekend, that cryptic preview — which purported to show the home video of a New York house party at the moment it erupts into chaos, as something gigantic, but never seen, attacks the city with huge explosives — had spawned its own universe of online traffic. Initially, people simply tried to find the title of the film, but as word spread that this was, in fact, the new unlabeled disaster film by producer J.J. Abrams, fans of Mr. Abrams’s secret-filled TV serial “Lost” quickly scoured the trailer for clues.

It didn’t take long for Mr. Abrams himself to add fuel to the fire, identifying www.1-18-08.com as one of the film’s Web sites, but ensuring fans there were others out there, waiting to be found. (Of course, Mr. Abrams and the production cachet he brings with him are part of the marketing bonanza: He neither wrote nor directed “Cloverfield.”)

The notion of secretive, online viral marketing is nothing new. A year before “The Blair Witch Project” stormed theaters in 1999, numerous enigmatic Web sites were launched to describe the bizarre, supernatural occurrences that the movie claimed had actually happened in the woods of Maryland. In 2001, Steven Spielberg’s “AI” used online games to capture the imaginations of ticket buyers. The previous year, Darren Aronofsky’s “Requiem for a Dream” offered an elaborate Web site that extended the fictional world of the film’s narrative in the form of a fake infomercial that was brought to life online. More recently, the teaser for the next “Batman” installment, “Dark Knight,” has used elaborate fan sites to reveal clues about the film’s production, including the first glimpse of the new incarnation of the evil Joker.

The high-water mark for interactivity among viral campaigns, however, may be the year-long hysteria that surrounded the 2006 release of “Snakes on a Plane,” a film that initially resisted its online fan base before reversing itself and bringing those fans into the filmmaking process. Based on suggestions from the public, New Line Cinema changed the film’s name back from a second variation, scheduled re-shoots to incorporate fan-suggested dialogue, and even organized a contest to select a fan’s music for use in the movie.

Yet for all the headlines the online mania caused, the movie’s so-so performance at the box office ($62 million worldwide) brought the establishment back down to Earth: While something may be a hit online with a few dozen, a few hundred, or a few thousand active surfers, a smash-hit viral campaign does not yield a surefire hit.

“The key is that the movie has to actually live up to what you’ve promised in the hype,” said Adam Paul, an online marketing strategist with New York-based ID Society Inc., an interactive design and marketing agency. “What we’ve started seeing less of are online campaigns that operate independently of the movie and more campaigns that expand the experience of the movie. By and large, the movie experience used to be about going to the theater and getting the popcorn, but that’s changed. People now want a more robust experience, they want to be involved and brought into the story line.”

Hence the puzzling marketing campaign for “Cloverfield,” which has been called a cross between “Blair Witch” and “Godzilla” — the first cinema-vérité monster movie. Since “Transformers” made its debut on July 3, Mr. Abrams and executives at Paramount Pictures have strived to indoctrinate fans as characters in the story, bearing witness to some unknown force laying waste to mankind. And while little more is known about the film’s core story than was known last summer (even the movie’s official Web site, cloverfieldmovie.com, gives little more than a two-sentence synopsis: “Five young New Yorkers throw their friend a going-away party the night that a monster the size of a skyscraper descends upon the city”), Mr. Abrams’s marketing game has offered detectives a few more shreds of evidence.

In a recent episode of the NBC series “Heroes,” fans took note of the name and logo of a soft drink that also appeared on the T-shirt of a character in the trailer for “Cloverfield” — “Slusho” — which led them to the Web site (www.slusho.jp) and a bizarre online commercial (viewable at YouTube.com) that seemed to have nothing to do with the New York disaster in the “Cloverfield” trailer. But that was until a new series of fake news reports was released online, all detailing the destruction of a drilling platform out in the middle of the ocean, supposedly owned by Tagruato, the fictional Japanese company that owns the fictional Slusho.

Meanwhile, on “Heroes” producer Greg Beerman’s Web log, a number of photos feature members of the cast prominently drinking or posing with Slusho. “The next group of photos falls into the ‘don’t ask/don’t tell’ category,” Mr. Beerman writes. “Their cultural significance will become clear in the coming months, so … pay attention!”

Confused yet? You’re not alone. But as this series of faux-YouTube clips and soda commercials was emailed among the “Cloverfield” devout, viewers got a video with more of the monster mystery they’ve been craving: Out in the middle of the ocean, an unknown force tears down a drilling operation (video is at cloverfieldclues.blogspot.com), fueling speculation that the monster in “Cloverfield” may actually be Godzilla.

And it gets better. Other secrets are sprinkled into the comment areas on these YouTube clips. Consider this peculiar, less-than-benign reaction to the video: “Do they drink Slusho in Cloverfield? They say the secret ingredient is ‘Seabed Nectar,’ they definitely recommend it be KEPT FROZEN.”

Will all this silliness pay off next Friday, when “Cloverfield” finally hits theaters? Unlike “Snakes on a Plane,” which relied almost solely on online buzz, “Cloverfield” is making some different decisions. For starters, Paramount plans to screen the film for critics next week, and Mr. Paul says that the studio is following the lead of other recent blockbusters such as “The Simpsons Movie” — which organized a promotion that remodeled 7-11 convenience stores to resemble “Kwik-E-Marts” — in balancing its online promotions with more traditional events. Just a few days ago, Paramount announced a MySpace promotion in which 200 of the film’s MySpace friends will be invited to “Rob’s surprise party” — the fictional party interrupted by rumbling explosions in the trailers — on January 17, the night before the film opens.

“While these viral campaigns are essential, I think the more people rely on new media, the more that traditional campaigns — the ones that show the ability to really get in front of people — will be the ones that stand out,” Mr. Paul said. “The ‘new’ and ‘different’ thing at some point will be something that goes beyond the Internet.”

ssnyder@nysun.com