I'm looking forward to seeing that!
If you want a few ideas, I think it'd be really cool to see those timed instances spaced out a little bit, and add in a few little scares that only come in once the player looks at a certain thing for a while. Maybe like if you look under the bed or at the light for long enough, a spooky face or creature fades in and then scuttles off. If you're using Unity for your engine, so you can pretty easily make these happen with a simple iGaze script, which're honestly pretty easy to make once you've made a few!
I'd also love to see a few different story lines in the form of secret notes or audio tapes that aren't any longer than a single sentence, scattered out through the instances to try guide some kind of narrative. Leave all of them completely ambiguous, and don't give the player any more than a few per playthrough, just to drive home that feeling of trapped hopelessness that you've got going on. That'd be as easy as scripting the interactable asset to spawn, then use an RND function to roll a number and call on an int assigned script for which story the player gets for that playthrough.
I'm just spitballing ideas. All in all, it is your game and I'm sure whatever you end up with will be something that you can really be proud of. Just keep at it and don't doubt yourself, you've got a great foundation already 😄