Nim Game has been played since ancient times. “There is 15, 16 or 17 balls in the row. Two players take turns removing balls from the row, but only 1, 2 or 3 balls at a time. The player who removes the last ball loses.”
You may play this game with kids using pencils or matches. Our Jan-2020 Challenge asks you to define the rules that provide a winning strategy using any BR/DM tool. Link