What is the largest amount of players at once that can play during a single chess game? I understand there is 3 man and 4 man chess but is there anything higher?
I've played 3- and 4-board "bughouse" with 6 or 8 people total, and can imagine higher counts though the logistics must soon become unmanageable.

In another direction, you can have a consultation game on a single board.  Such games used to be 2-on-1 (handicap) or 2-on-2 affairs, but in the Internet age the number of players on a side is virtually unlimited, as was already seen in this famous game back in 1999.