It would be a plot twist if all the game was a nightmare in the mind of MC. You know that in literature, Netflix (Love, Death + Robots) and also in a movie that I watched, a house can represent a lot of things and this house can have a conscience and will be a place where ghost or phantom live. Or making a little Jason with his machete.
It's the only way I could see that can be horror. From my point of view.
And maybe he is dying when he goes to the house.
It's only a suspect.
Psdt. Yeah maybe I smoke some weed to write this! Jajaja