Horror fans, the wait is now officially over — or it could be soon, depending on where you live. On Sept. 25, Paramount Pictures will finally release Paranormal Activity, the super low-budget indie that fright flick fanatics have been foaming at the mouth to see since its storied debut at the January 2008 Slamdance fest. On Sept. 24, the movie — about a young San Diego couple terrorized by things that go bump in the night — will screen at midnight at the Alamo Draft House in Austin, Tex. as part of über-geek Harry Knowles’ Fantastic Fest. Prepare to be freaked out. At a recent screening in Toronto, a packed audience gasped and screamed as they watched actors Micah Sloat and Katie Featherston become increasingly unhinged in the presence of a (potential) demon. Think Blair Witch, but in a cozy suburban house. (The latest trailer embedded here.)

The Fantastic Fest is just the beginning. Paramount will be holding additional midnight screenings on Sept. 24 in Los Angeles, New York, San Francisco, Chicago, Boston, Atlanta, and Seattle, and the following day kicks off a series of midnight sneak peeks in 13 cities across the country. If you’re not lucky enough to live in one of the chosen towns, you can try to bring the scares directly to you via Demand It, an online grassroots device that works like this: If enough people from the same (or nearby) zip code make themselves heard (you know, scream), the studio will send Paranormal Activity to their local Cineplex. “We felt the movie was so unique that it needed a unique platform,” says Amy Powell, Senior VP of Interactive Marketing at Paramount. “For the first time ever, fans will dictate where the movie rolls out.”

In an effort to get the word out, Paramount has also launched Paranormal Activity Twitter and Facebook pages, and come Sept. 25, it will equip theaters with computer stations for fans to log in and share their reactions. “All the anxiety that the audience experiences while watching the movie — we thought that might make them feel compelled to tell others what they thought,” says Powell.

If only Twitter could register blood-curdling screams.