Basing a movie on a popular video game is no guarantee for success at the box office, but that isn’t stopping Hollywood from playing the adaptation game.

No fewer than seven movies based on video games are in the works, and you can expect more after Silent Hill scared up the most moviegoers last weekend.

Based on the creepy franchise launched in 1999 by Japanese game developer Konami, Silent Hill made $20.2 million in theaters over the weekend.

As with the games, the film involves the psychologically harrowing search for a missing loved one. In this case, mother (Radha Mitchell, Melinda and Melinda) hopes to find daughter (Jodelle Ferland) and tracks her to the hellish town of Silent Hill.

Whether moviemakers will return to Silent Hill for a sequel remains to be seen. But the video-game-to-movie pipeline is flush with adaptations in the works:

•DOA: Dead or Alive, Aug. 25. Tecmo’s best-selling fighting games spawned this film; its hard-hitting harem includes Jaime Pressly (My Name Is Earl) and Devon Aoki (Sin City).

•Halo, 2007. King Kong director Peter Jackson is set to produce this movie based on the sci-fi game for the Microsoft Xbox.

•Spy Hunter, 2007. Dwayne "The Rock" Johnson, who starred in Doom, stars in this film based on Midway’s car-based spy game.

•Alice, no release date. Years after her trip to Wonderland, an adult Alice (Sarah Michelle Gellar) returns. Based on 2000’s computer game designed by American McGee.

•Resident Evil: Extinction, late 2007. The first two Resident Evil-based movies have taken in $90 million in theaters and were hit DVDs as well. That’s enough to put another zombie-fortified sequel in the works, with star Milla Jovovich returning.

•Castlevania, no release date. Based on the longtime Konami video-game franchise, this story involves Dracula and the vampire-hunting Belmont family. To be written and directed by Resident Evil/ RE: Apocalypse director/writer Paul W.S. Anderson.

That film could tap into the same horror-video-game success that Silent Hill did. About two-thirds of 2,100 moviegoers surveyed by the studio said they thought the movie looked scary, and 43% said they had played or heard of the game.

But with more than half of all Americans playing video games, "it is a gigantic audience that you cannot ignore," says Gitesh Pandya, editor of boxofficeguru.com. "What will excite them more than movies based on a video game? There are many flops, but they can be bigger hits than what else is out there."

Hollywood and the video-game industry have a "very symbiotic relationship," says Anderson, who also is co-producing DOA: Dead or Alive and directing the third Resident Evil.

"There has been a complete shift in the balance (of power)," says Doug Lowenstein, president of the Entertainment Software Association. "The game industry is, on most levels, equally powerful compared to these other media."

Even though no game-based movie has come close to the peak that Lara Croft: Tomb Raider hit in 2001, with $131 million, Hollywood will continue to mine video games for movie ideas. For one, they attract the 18-35 audiences. Plus, the games "almost serve as animatics or storyboards for the films in terms of action (and) costume design," says Mark Altman, writer/producer of the video-game-based House of the Dead films and a co-producer of DOA. His company, Mindfire Entertainment, is developing another video-game-based movie, Fear Effect, for 2008.

"I’m not surprised Silent Hill performed so strongly in its debut weekend," Altman says. "The same audience that’s going to Blockbuster on a Saturday night are the ones at home playing video games all week long."

But filmmakers will be challenged to match the cinematic advances in video-game technology achieved by the newer, powerful game systems such as the Xbox 360 and the Sony PlayStation 3, which is due in November, Anderson says. "We’ve got high expectations, and those have to be met with inventive, quality filmmaking."