The rules are simple, we all the players in the field where snow covers the land, there are a few drifts to hide behind but beware someone may sneak up on you.

 

When it is known how many are playing there will be an Init roll 1d100, to determine placement as soon as placment is assigned the first person will roll 1d (?) depending on how many players there are depends on what this number is the number rolled determines who you are aiming at in the lineup.
Then a 1d20 will be rolled this is your snowball, all you need do to hit your target is roll anything but a 1.
1= snowball falls apart no hit
2-14= light impact 1 point
15-19= moderate impact hit 2 points
20= Right on Direct hit 3 points