In the quest to develop games, it always behooves us to do side quests.
I've been reading the Harry Potter books lately, in anticipation of someday reading them to my daughter (dawww). I used to be a huge fan - though, I haven't read the last few since they first came out.
A couple aspects of game design leap out from just the first book. First off, Wizard Chess seems like a fun upgrade to normal Chess for casual players. The intelligent pieces improve the casual dimensions of the game in two ways; first, they add a dimension of negotiation to the game, where you can no longer sacrifice your pieces with impunity. Along with that, though, the pieces themselves are able to give newer players advice, and sometimes stop them from making a major mistake.
More fun to think about, though, is Quidditch.
Quidditch is absolutely ridiculous. Just to get it out of the way, a combination of football/soccer, dodgeball, and rat-catching is straight up ridiculous. Unfortunately, proper Quidditch requires a surprising number of magical props to function (sorry, college kids - you're playing an imitation!), and the game breaks without them. (If you need an overview of the rules, Wikipedia's got you covered.)
Once we get past the magical spectacle of the made-up sport, though, I do find a fascinating aspect in it - and one that informs possible game designs.
Essentially, Quidditch is two games played in parallel, related only spatially (they're all on the same pitch) and by score (the result of each mini-game contributes to a total score). In each match, six of the seven players on a side are involved in the football-esque game, where players try to score a ball through a hoop against a goal-keeper. Scoring is a gameplay event that happens regularly, and ticks up a team's score by ten points. At the same time, a team's seventh player is playing a different game - they are trying to find the Golden Snitch, a tiny ball that rockets around the stadium. Catching it gives a ton of points - 150! - and ends the game.
Most importantly, this is the only event that can end the game. The first mini-game can run the score up to arbitrarily large totals, and there are mentions in the book of games that last days or weeks - or even months.
In the books, we are also witness to one of the shortest games in Quidditch history. That's because Harry Potter is his team's seeker, the individual player responsible for finding the Snitch; his mini-game is a convenient narrative device to keep him above the action of the rest of the game, while also letting him win a game for his team with only natural talent.
Fictional worlds and narratives aside, there's something fascinating in an unbounded amount of time for a game. There are games that do this, to a degree (like Risk, which makes total and final victory difficult and time-consuming to achieve). But having the end-point be another game, occurring in parallel, adds a ton to the strategic possibilities. The tension between ending the game and preventing others from ending the game is real, and could flip-flop between players depending on how they're doing in the primary game.
It's been remarked by some that Quidditch is a strange and flawed sport, owing to the bulk of its rules being written before Harry Potter became a highly watched success. I think that JK Rowling hit it out of the pitch, though; the structure of her game is super inspirational, and it all feels unique.