“Writing Freeform Larps” is a new book just released by UK game designer Steve Hatherly. It’s guide to writing freeform/theatre-style/parlor larps:
Steve has a lot of experience and his online guides were a big help to me back when I started writing pregen larps in the secrets-and-powers style back in around 2008 (although I’d written some more idiosyncratic ones back in the 1990s). He’s coming from UK freeform tradition, and is one of the owners of Freeform Games and part of Peaky Games. Their games have been have been played a lot in NZ.
Steve’s guides provide a very structured, systematic approach which is quite nice when you’re dealing with a rush of ideas and not sure how to get it down or balance it across characters.