If you loved In the Mouth of Madness, try The Thing
A bridge between a film you've already seen and one most people haven't. Here's what they share, and what the second one does that the first one doesn't.
What they share
Both films are directed by John Carpenter, and they both carry the paranoid mood tag, and they sit in Horror / Mystery territory. If that's the register that drew you to In the Mouth of Madness, the second film will land in a comparable space — through a different lens.
paranoid
What The Thing is
Antarctica, early winter, a helicopter buzzing the US research station. A Norwegian helicopter crashes, a dog escapes, and the Americans uncover a burned alien creature at the abandoned Norwegian base. This paranoia-fueled sci-fi horror classic is best viewed on a cold winter night.
Ask 
ChatGPT
Claude
Grok
Le Chat
Perplexity
for a deeper bridge
ChatGPTClaudeGrokLe ChatPerplexity