Horror movies have always had a strange kind of magic. Even though they are full of blood, screams, and creepy moments, they are often really cheap to make. It doesn’t matter if the blood looks fake or if a mannequin stands in for a body. As long as the story hits just right, the audience is hooked.

Some of the most famous horror films were made on tiny budgets. The Texas Chain Saw Massacre cost less than $150,000 to make, and Halloween was made for about $300,000. Both of them made millions worldwide. Their grainy, raw style actually added to the scare factor. Horror doesn’t need fancy effects or awards to make an impact. Its power comes from the fear it creates, not how much money went into it.

Then came a little movie that took low-budget horror to a whole new level. Paranormal Activity was made for just $15,000 by Oren Peli. He did almost everything himself, including writing, directing, editing, and filming it with a simple home camera. The story followed a couple haunted in their house, and it looked so real that it felt like something anyone could film. The tiny budget actually made it scarier.

When Peli was looking for a distributor, the movie caught Jason Blum’s attention. Blum helped show it to DreamWorks, and later Paramount got involved. They even considered remaking it with a bigger budget, but test audiences loved the simple, scary original so much that only small tweaks were added for theaters, costing about $200,000.

The result was incredible. Paranormal Activity went on to earn $193.3 million worldwide. That made it the most profitable horror movie ever. What people first saw as a limitation—the simple found-footage style—became its biggest strength. Just one camera in the corner of a bedroom created some of the scariest moments in horror history.