KöMaL 2015 K451

In the game of rock-paper-scissors, players need to observe three rules: the rock blunts the scissors, the scissors cut the paper, and the paper wraps the rock. These rules decide which weapon wins. How many new rules need to be formulated if four extra weapons are added to the game (for example, matchstick, spectacles, telephone, stamper)? What is the fundamental principle of forming the rules, in order that the new game should be balanced, like the original game?