Grin: A Darker Age, is a free horror RPG game where all the rules for it fit on a single sheet of paper. Being a horror RPG, the chances for your character to make it out alive are somewhat slim. Monsters and madmen stalk the dark places and are just waiting to pounce out and get you. But wait, if it's free, what's the Kickstarter for? Well, they're looking to fund a book of scenarios for you to play. The book looks to be over 100 pages, so that one they'll be charging for.
The theme that runs through all of the scenarios is that they occur in our own past, though with a decidedly supernatural twist to many of them. Some of them also are written for just one GM and one player. This one-on-one interaction creates dramatic tension that you can't always get with a large group of players.
The Kickstarter campaign's about half funded with still 23 days left to go.