At the foot of an active volcano in Hokkaido, shouts ring out, competitors size each other up and snowballs whistle through the air in a very serious game of yukigassen ¡ª a sport with Olympic dreams.

The competition that took place over the weekend is held every year in Sobetsu, a town on the main northern island of Hokkaido, where this game ¡ª essentially a snowball fight ¡ª became a sport 37 years ago.

On the field, brute strength isn¡¯t enough. Japan¡¯s yukigassen federation emphasizes the ¡°mental challenge¡± posed by the game, in which players on both teams pelt their opponents while taking cover behind shelters.