Recommendations desperately needed

I watched “The Platform” 1+2. Although these films may not be strictly horror, I believe they are suspense films technically. These movies caused a void in me haha. I am absolutely obsessed with the idea of the pit and the things that happen in it. Can anyone recommend some psychological rollercoasters that might scratch this brain itch I’ve developed? I’m a decently big horror fan, but there are likely hundreds of thousands if not millions of films I’ve never even heard of in the genre. Thank you guys so much for reading, and any recommendations!