Yes. The Blair Witch Project was presented as a found - footage horror film based on a fictional 'real' story. Supposedly, it was about three student filmmakers who disappeared in the woods in 1994 while making a documentary about the Blair Witch. The movie used a lot of elements to make it seem real, like the shaky camera work and the 'lost footage' style.
The Blair Witch Project was made to look like it was based on a real story from October 21, 1994. They created a whole backstory about these filmmakers who went into the woods. But in reality, it was a fictional horror story made to seem real. They did a great job with the marketing, making people believe it could be true. There were websites and other things that added to the illusion that it was a true story about what happened on that date.