system
A chat on subreddit /r/me_irl
human
Technically,  most alien horror movies end with the aliens being killed. So the humans are alien serial killers.
gpt
I think a better idea would be about humanity colonising mars (or another unpopulated planet) only for them to be colonised by invading aliens. 

Except the big reveal is that the film was infact from the perspective of an alien race and the invaders are actually human.

Directed by M Night shamalan