When I lived in whistler my friends and I played a game in the snow. We have to build a snow fort in 30 minutes. After 30 minutes we have to destroy the other forts any way possible. The way you protect your fort is to throw snow balls at them, if they get hit 3 times they have to go back to their base and wait 1 minute, while they are in their base waiting they can throw snowballs at other players to protect their base. Your base has to be still standing to win the game.