John Conway died on April 11th

AS HE STROLLED in his dishevelled, friendly way through the hallways and common rooms of Cambridge and, later, Princeton, John Conway liked to feel he had about him everything he might require. Pennies in his pockets, to set spinning on the edge of a table to prove that more would fall heads than tails. A pen and paper for his game of Sprouts, which required spots to be joined up with curves that passed neither through old spots nor old curves. A board with a grid and stones, or peanuts at a pinch, to plot more of the games that fizzed from him continually. A couple of bits of rope for Twists and Turns, where four players, each holding an end, would change places turn by turn into nicely tangled permutations. And possibly as a party piece a wire coat-hanger, to bend into a square and whirl round his head, while ensuring that a coin balanced on the hook did not fly away. With any of these he would waylay the unwary, and challenge them to play.