1. Accessibility!

2. 2 separate core rule books, 1 for players, 1 for GM, do not bundle both into a single larger book.

3. Lower the Barrier to Entry

4. For introduction/basic/starter sets, see the whole subsection of recommendations to this the "right way" versus the majority of sets that do it the "wrong way".

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10 Other Optional Inclusiveness Considerations

1. Accessibility Guidelines

2. Core Rulebooks Guidelines

3. Starter Sets Guidelines

Stop relying on the Mentor/Apprentice model for new games/settings, it doesn't scale.

If an introductory/starter/basic set, actually design it as such. See the postings on the neuroscience of learning, and learning in layers. With a starter set, assume nobody at the table has any prior