Parlor Larps are a series of small books from Shifting Forest Storyworks in Palo Alto, California. Each book contains a larp scenario with eight pregenerated characters. They are designed to be extremely easy to just pick up and play. They can be played in a single room, with minimal prep, and scenarios work as written. The mechanics have a few intricacies, but at their core are pretty simple.
I have played two directed by the organizers ("Queen of Spades" and "All Saint's Eve"), directed two with my friends ("Hamlet" and "Garden Station Four"), played one with friends ("The Mirror Room"), and have run two at conventions ("Hamlet" and "Snow White"). I have three play reports.