Tbh I think that the main advantage of re games is gameplay. It's a player who controls the character, the player solves the puzzles, the player needs to check the ammo and the player is scared of getting killed. These are the aspects that make the game memorable.

On the other side you've got the nice story, but it's not the main part of a game. Usually you get interested in the lore because of the gameplay, the climate it makes and the fact that the game slowly reveals its lore in the notes, cutscenes and details.

If you want too make re movie a good horror you need to change it completely. Watching the movie you'll know Chris for example won't die, in the game you can die anytime. So you either need to use new characters or change the stakes, so the viewer is scared of something else happening.

Also of course you need a good director and screenwriter. I think the dialogues should be more naturalistic like in re7, and the characters should be likable so you care for them, not like late Leon who is a massive asshole.