I thought the article on MDA was very interesting, It thought me about the iterative, quality and quantitate. And how rules , system fun are the main components for creating a game. And then establishing their design counterparts. https://en.wikipedia.org/wiki/MDA I like how it also explains the ascetics, and goes into what makes a game fun. for example games like quake would express a challenge , the sims and final fantasy, the sims express the discovery, fantasy, expression, and Narrative etc. http://gamedevelopertips.com/mechanics-dynamics-aesthetics-game-design-theory-behind-games/ The document on hearts clubs diamonds and spades was also very interesting it talks about the inter relationship of two dimensions of playing style. https://www.meeplemountain.com/top-six/top-6-abstract-games-games-about-nothing-and-everything/ ( Random Hands Gaming )