The race is on to fill the “Lost” void.

A number of major nets are fielding ambitious dramas that aspire to the same kind of dense, mystery-thriller-style storytelling that proved so addictive to “Lost” fans around the world for six seasons.

Broadcasters and cablers alike are trying to absorb some of the Losties who are surfing around for a new show to obsess over.

Among the hopefuls are NBC’s “The Event” and “The Cape,” AMC’s “Rubicon,” ABC’s “No Ordinary Family” and CW’s “Nikita.” HBO is venturing into this territory with its upcoming “Game of Thrones,” which marks the pay cabler’s first foray into the sci-fi sphere.

Fox’s “Fringe,” which is heading into its third season, also has high hopes of picking up steam among “Lost” fans (thanks to its J.J. Abrams pedigree) who might have been reluctant in devoting the time necessary to follow every new twist and unravel each new mystery that both shows present.

Nets, of course, hope all their original series generate fandemonium. But shows like “Lost” and “The X-Files” have demonstrated that there are even greater benefits to be reaped from series that challenge fans to solve a central puzzle that drives much of the plot development. What better way to keep viewers coming back faithfully week after week?

The louder the online conversation about each episode — through blogs, social media, Twitter and YouTube, et al — the better. DVD sales can be robust on shows that fans like to watch multiple times in their search for clues and insights. This kind of attention also builds a strong base for sales of ancillary products (everything from vidgames to T-shirts), such as the $1 million-plus raised recently by the auction of “Lost” props and memorabilia.

Attempting a heavily serialized, mythology-saturated show comes with plenty of risk, however. Such shows tend to require visual ambitiousness and great scope. As ABC discovered in its many attempts to find a tonal companion to “Lost,” with shows like “FlashForward” and “Invasion,” it’s hard to get the mix of character development and plot intrigue just right. The roster of shows that tried but failed to ride “Lost’s” game-changing paradigm also includes Fox’s “Da Vinci Code”-tinged “Vanished” and ABC’s bank-heist backstory “The Nine.” Even when a show clicks, it can be hard to sustain a high level of suspense, as NBC’s “Heroes” demonstrates.

For TV studios, serialized dramas are a big risk because they rarely do much business in traditional off-network syndication — even “Lost” sold for modest dollars to Syfy a few years ago. That puts more pressure on studios to generate profits through DVD sales, international licensing and merchandising.

“Conspiracy is something people are attracted to, and in the last couple years, the interest in conspiracy has never been greater,” says Joel Stillerman, AMC’s senior VP of programming. “?’Rubicon’ was supposed to be a broader-appeal show with maybe a more male-skewed demographic, but the idea of solving a mystery can be enjoyed by anyone, so I feel a following can be built from this show.”

That’s not necessarily what Henry Bromell, the scribe and showrunner of “Rubicon,” the thriller starring James Badge Dale as an analyst at a federal intelligence agency on the trail of a government conspiracy, is trying to do.

“If you make a show about a conspiracy, you have to write a show like ‘Lost’ or ’24,’ and I didn’t want that,” Bromell says. “By episodes four or five, we wanted to slow this thing down and keep things completely grounded in reality, and that included the conspiracies as well.”

Bromell and his team were trying to make something that looked and felt like a movie but moved at the pace of a TV show. (In its first month, the show has averaged 2.1 million viewers when DVR playback is included.)

“I believe in my gut there is an audience for a show like this,” Bromell says. “Of people I have talked to who have watched the first four episodes, one of them already said he watched all four of them four times already. I told him you gotta stop.”

While “Rubicon” is looking to build that following from scratch, AMC at Halloween will unleash “The Walking Dead,” a show set in a zombie-infested landscape that drew a strong response at Comic-Con and has given the network something with a presumed fanbase prior to its premiere.

“It is not exclusively why we brought it, but when you go to something like Comic-Con and realize you don’t have to launch (your show) from absolute scratch, it’s a huge relief,” Stillerman says.

Fan hubs like Comic-Con have served as a platform to build a following, but networks have taken extra steps in marketing to get auds’ attention about their upcoming slates.

Like “Rubicon,” NBC’s “The Event” hinges on a mystery, with the net unleashing an array of promo spots that tease at what the show could be about.

NBC marketing prexy Adam Stotsky says with every NBC show, the network strives to make sure the key demographic and core audience is effectively targeted.

With “The Event,” Stotsky says, “Our marketing is focused on sowing the seeds of this mystery and designing a campaign that captures the visceral sense of this experience that the show delivers.”

Still these shows are trying not to fly too close to the flame — and to avoid the fate of “FlashForward,” which never recovered from having been marketed as “the next ‘Lost.’?”

Stotsky understands the importance of delivering something fresh.

“Today’s consumer is surrounded by marketing and is acutely sensitive to derivation,” he says. “We spend a lot of time tracking our competition, dissecting their work, understanding what works, what doesn’t and discussing how to develop our own unique point of view.”

David Glanzer, director of marketing and public relations at Comic-Con, warns that aspiring shows, including several set to bow in the coming weeks, have to deliver beyond the buzz.

“You may bring something to Comic-Con and it may have a great trailer and great footage, (but) if it doesn’t live up to those expectations, people are going to turn the channel,” Glanzer says.