"Paranormal Activity" was a game-changer in the horror genre, influencing a new wave of found-footage films. The movie's success can be attributed to its low budget and innovative marketing strategy, which included a viral campaign and limited release. The film's grassroots success spawned a franchise, with multiple sequels and spin-offs. Moreover, it paved the way for other found-footage horror films, such as "The Last Exorcism" (2010) and "The Taking of Deborah Logan" (2014).