Soccer Zero is a variant of soccer using an ultra-light ball (~1/7th as heavy as a normal 5). The reason for the change is a fear of CTE, a brain disease plaguing some retired NFL football players (https://www.youtube.com/watch?v=nzc0Lrxw3KY). It is generally thought that soccer players don't need to worry about CTE. However, not everyone agrees (https://www.youtube.com/watch?v=Hy_TTbv14RQ), and studies (https://www.facebook.com/notes/safer-soccer/does-soccer-cause-brain-damage-ie-cte/997031797105707/) will probably be coming out on both sides of the debate for decades to come. This game is for the more cautious "belt and suspenders" athletes wishing to take "zero" chances. Play seems to favor agile players and penalize overweight players (like those can't run fast, but who are great at passing a regulation ball very long distances). Games are in Silver Spring, MD. They are reffed. Clean red and blue pinnies are supplied.
We use an injury-based foul system. You can use your hands to protect yourself from the ball; hand balls are only called if you did it to gain an advantage. Yellow cards are 1/2 point to the other team. Strong kicks of balls to anyone's head ("face kicks") are yellow-card fouls even though the ball is so light it probably doesn't matter, which is mostly good because it penalizes inconsiderate play, something we really do care about. Reckless players or anyone getting a red card is banned. (Before heading, you need to have an idea of where other nearby players are.)
A weekly invitation including a recap of the prior week's game is sent out to any players who want to read it. See here (https://www.meetup.com/safersoccer/boards/thread/23643732/0/).