Board and pieces
Four-player chess is played on an 8x8 board that is extended by three rows of eight squares on each side. Quite simply, it is just a 14x14 board with the 3x3 corners removed. The board has 14 files, assigned the letters a-n, and 14 ranks, numbered 1-14. The overall game is played with four regular sets of chess pieces, all of another colour. The colours used throughout this book are red, blue, yellow and green.
Players
The game is played with four players, each with their own set of pieces. The players will hereafter be referred to as Red, Blue, Yellow and Green, corresponding to the colour of their respective sets of pieces. Red may be the first player and makes the initial move. Therefore, the standard board orientation is from Red's perspective, i.e. Red is shown at the bottom. The next player is Blue, who is seated on the left side of Red. Yellow may be the third player and is seated across from Red. The last player is Green and is seated on the right side of Red, across from Blue. The overall game continues in clockwise order, i.e. https://worldseniors2014.org , followed by Blue, accompanied by Yellow, accompanied by Green and then Red again etc.
Initial position
Looking from each player's perspective, the pieces are arranged exactly the same way as in regular chess, other than for Blue and Green the king and queen are swapped. That is, the rooks go in the corners, the knights are put close to the rooks and the bishops are put close to the knights. All kings are put on light squares and all queens are placed on dark squares. The pawns are put while watching pieces. The board should be oriented such that the lower right square of the 8x8 central portion of the board is really a light square, when viewed from Red's perspective, just like a regular 8x8 chess board. (If one would imagine a complete 14x14 board, the "n1" square on underneath right should be a light square.)
When it comes to files and ranks, Red's pieces are put on the initial rank and the pawns on the next rank, Yellow's pieces are placed on the 14th rank and the pawns on the 13th rank, Blue's pieces are put on the a-file and the pawns on the b-file and Green's pieces are put on the n-file and the pawns on the m-file.
Rules
You can find two main variants of four-player chess: Free-For-All (FFA) and Teams. In the FFA variant each player plays by himself and in the Teams variant the players across from each other form a team. Pieces move exactly the same way as in regular chess and castling and en passant captures are also the same.