Introduce a character that's a teacher so sick of cellphones in their class they bought a jammer off the internet. Make that character the serial killer's first victim.
Logical solutions to problems don't happen in many kinds of horror movies. Even the tiniest bit of common sense applied would destroy so many, cell phones or no.
That’s why I love Cabin in the woods. They make it a creepy movie, but also make fun of all the common horror tropes by having the haunted grounds be a very orchestrated event.
“Oh no my cell phone doesn’t work”
It’s because the creepy org turned on a cell phone jammer
“Why don’t they just leave?”
The creepy org blows up a shit load of tnt to make the tunnel collapse
"Why don't they find an alternate route out?" The creepy org put a fucking force field around the area.
That movie definitely ventured in to silly territory, but then it was quite directly a well-meaning parody of horror movies that kinda' HAD to get a bit silly to do too much with the premise.
Let's walk right by the car we got here in and go house in the creepy building that we think the killer lives in and that we were too scared to enter before he killed our friends!
Oh my god! It's the killers childhood home where he brutally killed one of his family members in each room! Let's hide in there, but we should each find a hiding spot in a different room.
It would be kinda funny for someone to make something that starts as a horror movie but then everyone acts in a sensible manner without contrived reasons for their efforts failing, resulting in the whole dangerous situation falling apart over the course of the plot until its more a sort of parody of horror movies than a proper example.
I want a horror movie where some of the heroes are genre-savvy, Practical Guide to Evil style. I picture it starting as a horror, and shifting into a kind of heist storyline
The best horror movies are the ones where all the characters act in a highly capable and intelligent way and the monster/force/whatever still keeps beating them. Like The Thing. Or Alien.
Not just cellphones but every house now is equipped with a camera on the doorbell and possibly several more throughout the house. Back in the day serial killers basically just had to not be around when the police showed up and had a pretty good chance of just getting away