Why you should check this out: a recipe-book of ideas and inspiration for mechanics and flavour for bases.
Style: the writing is conversational making it friendly and approachable. A mixture of 2-column and 1-column layouts are used, with clear chapters and headings breaking down the content.
Structure: the thoughts of the designing and intent of the mechanics are discussed at the start of the document and of each chapter which is great to know what to expect.
Content: there are a lot of great ideas for mechanics and flavour for bases. Careful thought has gone into not making these too prescriptive, allowing a referee to pick and choose the ideas that would work best for their table. I love the invisible parrot that repeats conversations.