Principle 6.1
Play is what we do when we are free; play is what we do to be free.

I think principle 6.1 is a very important point. As stated in the book, play is sort of the ultimate end-in-itself: there is little to be gained as a result of play; the play in itself is the gratification. Thus, it would be definitely higher up on a list of needs, like a hierarchy devised by a certain Maslow fellow. Aggregating these axioms—that principle 6.1 holds true and that play is "unnecessary" in basic survival (the quotes do a lot of heavy lifting here) due to its status as an end-in-itself—I think it is fair to introduce an interesting point raised by philosopher Stephen Cave called the Freedom Quotient (FQ). Unlike what one might assume, the FQ does not have to do with your USA flag emojis to word ratio in one's quotidian writing (🇺🇸🇺🇸🇺🇸), but rather with three criteria:

• "the capacity to generate options."
• the ability to "choose between them in a meaningful way."
• the ability to "carry out the choices we have made."

This complements nicely the first part of principle 6.1: when we are free, we are able to execute Cave's three steps of freedom, and fulfill higher-order needs. If one was worried about their basic needs, their FQ would be severely hampered by the fact that they would have a diminishing capacity to generate options other than those that contribute directly to them obtaining said basic needs. It is only because we have the affordance to act these three steps that give us the privilege to play. Maybe more directly, Cave's FQ system interacts clearly with the second part of principle 6.1. When earthly circumstances limit one's ability to be free according to Cave's metrics, play can provide a sandbox in which these three criteria can be met. A very unfitting example would be, hypothetically, if I were auto-limited in freedom by the amount of work I have to do (albeit already a very high-level need in the hierarchy), I spent my time playing, say, Minecraft where I am not limited by such institutional requirements. Not to say I do this; in fact, I don't: I obviously do my homework before leisure. In this example, this person would regain their autonomy and their abilities to generate, choose, and carry out choices within the scope of the game. Being that games are "played in hyper-1st person" (principle 6.8), this immersion satisfies a higher-order level of need when it can't be satisfied in the real world.

Principle 6.6
Elegance is simlpe mechanics giving rise to complex dynamics.

I probably already spent 400-500 words on the first principle, but I just wanted to say that I highly agree with this principle as well. When I took 247G, one of the biggest disagreements we had as a group while designing our card game was that fact that I was adamant that our games had too many mechanics for far too little dynamics. One of the "model card games" that I constantly referred back to was Exploding Kittens, which is in my mind one of the best card games ever designed (there's a reason why it broke Kickstarter records). Despite the limited number of card types, there was so much dynamics to be had such that each game was a unique experience, even between the same people. While we ended up creating in my mind, a game close to Exploding Kittens' ratio of dynamics and mechanics called Capybara Clash, I think that experience really epitomized this principle.