I asked one of the guys who was a part of this about some of the rules and such. (I asked one of the guys who had a fox mask with really shaggy hair).
He pointed out that the Sakuracon forum had the rules for this on a thread so here you go.
Official Rules for the Cosplay Chess Game
The Basics of the Game:
There will 38 main players, two chess players who will be controlling the moves of all the pieces on the board, and the emcee’s. There will be at least 38 spaces available, but more will be allowed in case a person has to drop out or misses the pre-game meeting.
How the Battle System Will Work:
1) When a move is made by the chess players, and that move results in a piece being taken, a battle will take place.
2) The other pieces not part of the battle (All pieces except the two involved) will remove themselves from the board and the two pieces will battle. The use of ‘attacks’ and special moves is encouraged, and the back up players, if called on can join the battle. (For example, if Edward Elric calls upon the ‘minions of minis’ to attack, characters that fit that description can join in the battle as long as they are not currently on the board.)
3) The attacker will always win.
4) The two Pieces will battle and put on a show for the audience, and "die" in a dramatic way. Battles should last no longer than 3 minutes, if the battle goes over the time limit, the emcee will call on the attacker to ‘Finish Them’
5) The loser will leave the board and watch the rest of the match; however, they can get back into the game if a pawn makes it to the end
6) After the losing piece leaves the board, all the other pieces will move back to their previous positions. Positions will be marked, so you will have to remember the number of your space before the battle started.
Rules of Participation
1) There should be little to no physical contact between pieces not currently engaged in battle (i.e. little to no pushing or shoving the piece next to you, even if they are your 'enemy.') During a battle, you may not touch the piece you are ‘fighting’ unless you ask and they consent first. This rule is taken very seriously. If you hurt, injure, or inflict any discomfort on another player in any way, shape, or form, you will be taken out of the game IMMEDIATELY.
2) The pieces should be easily recognized. No original characters or made up variations of characters will be allowed.
3) If using a weapon, it must be peace bonded, and if the staff believes the player is violating the rules of peace bonding, that player will be removed from the board and replaced.
4) Being in character is encouraged! So is play-acting! Battle cries and the like should be loud (We need to hear you!) and can use other characters, except the ones who are on the board already. However, as stated in rule number 1, do not go over board and harm someone.
5) The same basic rules at the Masquerade are enforced, no projectiles, flames, explosives, live steel or any other sharp pointy object will be allowed during the game.
6) The players involved will have their position decided and told to them a week before the con, and will be required to attend a mandatory pre-game meeting. Not attending the meeting will mean you have forfeited your place and it will be given to someone else.
7) The players can apply for a position, and will requested to list a first, second, and possibly third choice. We will work to accommodate as many first choices as possible. If no position is requested, you will be put into a drawing for a pawn position.
8) The players will need to include the name of the character they are going to be cosplaying and a picture of the character (This is to avoid getting a character twice on the board and to make sure all the costumes involved will not be over elaborate and lend themselves to be damaged easily)
He mentioned that there needs to be a rehearsal so everyone understood the rules and wouldn't go overboard. If you didn't go to rehearsal, you were dropped and someone on the waiting list took your spot.
As someone who watched this, my one complaint was I had a hard time telling one piece from another.
By the way, some of the highlights included Snake (Metal Gear) vs Haruhi (Ouran) and Ichigo vs. Cloud. Very fun stuff. At the end when things were starting to wind down they decided to skip checkmate and make it a battle royale.
By the way, I would also like to be a part of this if possible. ^_^