A bit late to the discussion but here in the UK various groups run what are known as Megagames but which are really Braunstein-a-likes. The organisers arrange a location, a scenario and a team of referees then gather players for a day's gaming. I played in quite a few over the years a Battle of Britain game at Sandhurst, a Morgan's Raid on Panama, a sci-fi invasion, a World War One game. All involve about 50-80 people and for a modest cost provide a day full of entertainment. They don't seem to have a problem in getting enough players together.
Megagame Makers
Megagame Society
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