Fifty people awake to find they are standing on glowing red spots in a circle in a dark room. They quickly learn that they are playing a deadly game – every few minutes one person is killed instantly by a shock from the hemisphere in the centre, their body then dragged out into the darkness by unseen forces. If they step off their circles they also die. It takes them a few rounds, and a few deaths, to understand that while they cannot prevent the scheduled rounds, they can choose who dies in each round. Circle is a literal, minimalist version of the balloon debate – if the balloon is losing altitude and you can’t all survive, who gets chucked out of the balloon and how do you persuade others to do the chucking. The starting fifty are diverse enough to (loosely) represent all of humanity. As the players learn how to vote for each other, alliances and dividing lines appear around age, race, gender, sexuality, politics and profession. Players try to use this to their advantage, but if the...