E gave me this book for my birthday last May, to nudge me to stay playful now I’ve turned 50 🙂

Play: How it Shapes the Brain, Opens the Imagination, and Invigorates the Soul is from 2009.
I thought the first third had the most useful substance for me. The discussion of play ‘archetypes’ was helpful. What I realised reading it, is that the types of play that generally stand out to me are the ones I dislike (the joker that tells jokes, the director where it gets manipulative, the competitor), and that the things I generally enjoy (the explorer, the creator, the storyteller) I don’t think of as play mostly.
It mentions ‘play history’ but doesn’t really help you explore your own.

A key claim is that staying playful is a way of staying flexible and adaptable in the face of a changing environment. It posits that the opposite of play isn’t serious work, but depression.

Most of the rest was about evolution as well. That is interesting, and some elements did jump out to remember, but I at least didn’t get what point it was meant to make, other than seemingly repeating the claim above multiple times.