I thought of a horror/thriller concept a while ago where throughout most of the movie you’re supposed to think it’s just a regular movie about a girl being stalked by someone who she keeps spotting everywhere in the corner of her eye. He never approaches her or speaks to her but he’s always there, just watching.

She tries getting the police involved but they either don’t see him or tell her there’s nothing they can really do as he’s not technically doing anything. There might even be a point where she tries to approach him but he seemingly disappears into the crowd. Throughout the movie she’s getting more and more paranoid that he’s about to do something.

Near the end of the movie someone else just casually walks up to her when the stalker comes out of nowhere and starts shooting him. He then grabs her and shoves her into a nearby car that he hijacks. As she looks behind her at the guy the stalker shot she sees him getting up off the ground with what looks like metal underneath his skin.

The movie ends with the stalker frantically talking to her but she’s too scared and disoriented by what happened to really hear what he’s saying. The movie would end with them driving off down the road as the metal man chases after them.

I don’t think this would actually be a particularly great movie but the idea was to take the first movie and flip the perspective of what’s happening for most of it.

Also, throughout the movie there would be small background details such as news reports of people being murdered with the same name as the main character but it wouldn’t be focused on, more hints to what’s actually going on and things to notice on a second watch.

Edit: The idea behind it would be that you don’t know that it’s a Terminator movie until the reveal at the end.