1. (7,3)
Four-Player Infinite Chess - The Battle of Morgarten!

Game notation has odd numbers for McGoohan and Luke_Hands. Even numbers are hitthepin and me. So far:
1.(7,3)...(5,5)
Game notation has odd numbers for McGoohan and Luke_Hands. Even numbers are hitthepin and me. So far:
1.(7,3)...(5,5)
This is a four-player version of "Chess on an Infinite Plane".
Representing White is @McGoohan and @hitthepin (yellow and blue).
Representing Black is @Luke_Hands and @vickalan (green and red).
The starting position and move order is shown here:
Each army has 38 pieces, for a total of 152 pieces on the board.
All pieces move as in classical chess, with the "extra" three pieces moving as follows:
Chancellor (C) - Moves and captures as rook + knight.
Hawk (H) - Leaps exactly 2 or 3 squares in any orthogonal or diagonal direction. The leaping move means it can jump over other pieces.
Guard (G) - Moves and captures the same as a king but is not affected by check.
Pawns play the same and promote at the same rank as in classical chess. White pawns promote at rank 8, and black pawns promote at rank 1. Pawns can promote to chancellor, hawk, or guard in addition to queen, rook, bishop, or knight. Pawns may capture and be captured en passant with the same rules as in classical chess.
Other rules:
Capturing: Capturing a teammate's pieces is allowed. (This may be seen for example when a pawn captures a teammate's piece to promote).
Communicating: Allowed between teammates, but each player controls his own pieces.
Time control: Three days max per move.
Win Condition: To win a team must capture one of the opponent's kings, and checkmate the other. Kings still cannot be left in check, or placed into check (so can't be moved for an exchange). The first checkmated king is subject to capture (and removed from board). The lone surviving king must then be checkmated by the winning team.
Addendum (based on discussion at #178):
1) When a team has two kings on the board, and one player has a king in checkmate, the player may not move the king, but may move any other piece. If the player has no other pieces, then he skips his turn.
2) When a team has two kings on the board, and both kings are in checkmate, then the opponent has won (a double-checkmate).
Castling: Castling is similar as in normal chess, except the king moves to a square which is intially occupied by a guard. The rook from that side jumps over the king and finishes adjacent to the king (see diagram). A king may castle within his teammate's army. Castling is a king move, so a player may castle his king with his teammate's rook (but not vice-versa). To castle, all squares between the king and the involved rook must be clear within the army of the king's destination. All other rules of castling are the same as in classical chess.
Other:
There is no fifty-move rule. Draws can only occur from stalemate, threefold repetition, agreement, or a proven case of insufficient material to force checkmate.
All other rules are the same as in classical chess.
Move Notation:
Numeric coordinates such as (x,y) are used to identify piece locations as (file#, rank#). Parenthesis are used around each coordinate. Three examples of a move notation:
1) A rook moving from (8,4) to (1,4):
R(8,4)-(1,4) or R(1,4)
2) A rook moving from (1,4) and capturing a piece on (0,4):
R(1,4)x(0,4) or Rx(0,4)
3) A pawn advancing from (-1,7) to (-1,6):
(-1,7)-(-1,6) or (-1,6)
McGoohan starts as yellow. Good luck to both sides!