Every October back in my primary school I would become obsessed with playing conkers.
The game of conkers would consist of finding a conker and putting it on a piece of string. You would then find some else that has done the same with their conker and they then take turns hitting each other's conker using their own. One player lets the conker dangle on the full length of the string while the other player swings their conker and hits. To win you need to break the other person’s conker off the string.