Blumhouse recently made horror history with a Halloween’s launch of FIFTEEN – the first interactive POV slasher film to use the Periscope app, allowing audiences to actually determine the outcome of a killer’s reign of terror in real time. While the end product appears totally spontaneous and improvisational (and much of it was), it’s also the result of meticulous planning and precise coordination of cast and crew.

[If you missed the live broadcast, you can watch the entire film here, including the audience’s tweets to the killer. Be sure to watch that first, because the following clip is packed with spoilery stuff.]

The following behind-the-scenes featurette follows the creative process of writer-director Gavin Michael Booth, producer Ryan Turek and their team in bringing FIFTEEN from concept to execution (no pun intended), including interviews with the killer (Neil Napier) and his victims. Check it out!