Keen Ice

Championship curling, from inside the hack. Throw a 19.96 kg granite stone 45 metres down pebbled ice and watch it break four feet in the last five, because the running band melts a film under itself and its front scratches pebble the back rides over. Sweep to steal three metres of run and hold the line; sweep one side to steer it. The whole World Curling rule book is here - the five-rock free guard zone, the hog line, the burn, the hammer, the blank end, the button measure - plus an eight-game season, a 24-drill practice range and an opponent that picks its shot by expected end value.