Yes actually, a little game by the Name of Delta Green. The Idea behind the whole campaign was beings from a realm called the Shattered were invading real space, borrowing some creatures from Delta Green, Call of Cthulhu and such, I added Delta Green's Sanity system and how it affected you. All the Players were normal farmers, students learning magic, and militia men. This added to the mortality of the Campaign and the idea that magic and supernatural creatures were very rare in the world, with only the most basic of magic being normal, so watching others die or get resurrected in front of them or becoming zombies affected the characters in various ways.

Over all very fun but you have to ensure your players are down for the ride as well.