Lovecraft X The X-Files tabletop roleplaying game. Delta Green has been kicking around for decades and so it has so much modules written for it, critical for an investigative RPG like this where the devil is in the details and it’s much harder to run a game like this without any supporting material.
I’ve never played or ran a game like this but reading through both rulebooks and some modules has left me curious to try. Even if I never play the game itself, the rulebooks are a goldmine of ideas to reuse elsewhere.
The module Impossible Landscapes based less around the Lovecraftian mythos and more on the King in Yellow, and the danger of memetics. Reading through about half of it was really eye-opening because of how both evocative and detailed it was. I feel confident that although this kind of roleplaying experience is likely to be a little harder to run, I think it would be rewarding to do so, especially with the help of modules like this.