ALLIANCES
In two-player chess, opponents sit opposite each other.  But in four-player chess, it is more natural and easier to attack the players to the side than it is to attack forward.  This makes players sitting opposite each other more likely to form natural alliances, and players sitting side by side to become adversaries.  It appears that four-player chess favors the formation of opposite-sitting players as a team.  In fact, the early rules of four-player chess required players sitting opposite of each other to be partners, and as partners, they could not capture or attack each other's pieces.

4-Chess - Adversaries and Allies does not force a partnership on any player.  Instead, players may act as allies or adversaries at will, changing strategic alliances as the game progresses and as changing circumstances might require.  One player's pieces may attack and capture any other player's pieces, or refrain from it. 

All things equal, a team should have a geometric advantage over a lone player.  However, all things are seldom equal in real life.  Some individuals are very compatible and form a formidable team.  Other individuals may be so incompatible that the alliance is counterproductive.  In general, however, once two players form an alliance, the other two players should also form an alliance in self defense.  Otherwise they will individually be at a tremendous disadvantage against the team.  

There is great merit in formally forming an alliance.  But remember also that any player at one time or another may be an unwitting ally or adversary to another player.  And while everyone expects natural opponents (side-by-side players) to be adversaries, even they may occasionally team up to punish an especially unruly or obnoxious player. 

PERCEPTION & DECEPTION
Unlike early four-player team chess, which required all players to refrain from divulging their intentions, 4-Chess - Adversaries and Allies allows players to talk to each other and comment on the game.  Players may offer each other advice , which may be devious and intended to confuse and mislead.  Players may also make promises that they may break.

While honesty and trust are valued traits to pursue and practice, being open and transparent in chess is a disadvantage in that it can give a decided advantage to adversaries who do not reciprocate with the same openness and transparency.  In competition as in real life, it is often important to gain an unnoticed edge in order to prevail, so silence is often the better strategy.  

Once an individual is known for uttering falsehoods, he loses effectiveness, and may find three players have teamed up against him.  And once a betrayal occurs, very strong emotions for revenge are created that begin to affect plays.  Even the most Spock-like human will find it difficult not to waste a move in revenge for a real or imagined wrong or  betrayal. 

Chess requires a very disciplined logic to win, but the insertion of the possibility of deceit and betrayal can causes strong emotional conflicts to enter into the fray, confusing planned outcomes, just as in real life.   Players must learn to see through the misleading rhetoric and read the board for clues.    It is the introduction of the possibility of deception and betrayal into the game that makes it more like real life and exciting to play for everyone.  Once again, though, silence may be the far better strategy.

CONFIGURATION SYMMETRY and FAIRNESS
Four-player chess configuration can greatly affect a player's chances to win.  The absolute requirement for a competitive game should be that all players begin at the outset with an equal chance to win.  The three most commonly used piece configuration for chess only involve queen and king placement, all other pieces always face like pieces across the board (pawn to pawn, rook to rook, knight to knight, and bishop to bishop).  The order of play, clockwise or counter-clockwise, does not affect fairness.

1st Configuration:  All queens are placed to the left of the king (white queen left of white king, etc.), or, all queens are placed to the right of the king (just the reverse of all queens to the left)
    Fairness:  Perfectly fair configuration for both two-player and four-player chess.

2nd Configuration:  All queens are on a white square (most common four player configuration), or, all queens are on a black square (just the reverse of all queens on a white square)
    Fairness:   Perfectly fair configuration for both two-player and four-player chess.

3rd Configuration:  Queens face each other across the board (as in two-player chess)
    Fairness:   Perfectly fair in 2-player chess.  Biased (unfair) in four-player chess.  NOT RECOMMENDED in four-way chess.

For further discussion on symmetry and bias, click on the link below.

 SYMMETRY & BIAS

FAVORED OPENING 
In four-player chess, the queen is even more powerful than in two-player chess.  And initially the bishops are much more useful than the rooks.  Every player will want to free their queen on the first opportunity by King's pawn to King's row 4, which not only frees the queen to attack diagonally against her king-side player, but also allows the king's bishop to attack the queen-side player.

COLORS
Four-player chess is played with four sets of standard pieces on an expanded board.  A set consists of 8 pawns, 2-rooks, 2-knights, 2-bishops,  1-queen, & 1-king.  All four players must have a different color (or style) sufficient to readily tell one player's pieces from another player's.  In the depiction above, for example, white, green, red and blue are used. 

In the depiction below, white, black, green and blue are used.  When black and white are used, black traditionally goes to the left or right of white, because they are traditional opponents (adversaries.)  Any color is fine as long as it is readily differentiated from the others.  Any unique combination of color and style may be used that sufficiently differentiates the players.  

PLAY SEQUENCE
If a white color is used, it traditionally moves first, then each succeeding player on the left (or right) moves in turn.  If  no actual white color is used, or if two players both have a white color (but different styles), then the players must pick who is to start.  Because the first player has a perceived advantage to win, each succeeding game should start with a different player.  Play can be clockwise or counter-clockwise.  Successive Games may alternate between clockwise and counter-clockwise play, which may add new challenges for the players.

ALTERNATING CONFIGURATIONS
Players holding successive marathons may want to alternate configurations so new strategies are required in succeeding games.  For example, queens on white, next game queens on black, next game queens on left, next game queens on right, and then repeat (configurations 1 and 2, above.)  Remember to avoid queens facing queen (configuration 3, above) as this configuration is biased (unfair .)

BOARD DESIGN
The board design is at least 300 year old.  It has been expanded from an 8x8 (64 squares) to a 14x14 (160 squares) with the 3x3 corners removed.  The expansion is necessary to accommodate the extra set of players with a reasonably-sized battlefield.  Many four-player board designs have been proposed, and tried, but this has become the de facto four-player standard.  The board colors should be sufficiently contrasting to aide the eye to differentiate rows, columns and diagonals., and still allow the pieces to stand out.

2.  On reaching its end row (its 14th row) the pawn may not be exchanged for another piece (such as a queen).  The reason for not allowing an exchange is that the 14th row is controlled by a player who is more often than not allied with the advancing player -- making exchange too easy.  

3.  On reaching its end row (its 14th row) the pawn may reverse its direction, advancing in the opposite direction.  On again reaching its base row, the pawn may again reverse direction.  This march up and back can continue as long as the game goes on.  It has been suggested that an arrow or other marking be placed on the pawns so the players can tell which pawns are advancing in which direction. 

4.  A pawn can be exchanged for another piece (such as a queen) only on reaching the 1st row of a player to his side.  This is very difficult to accomplish because the only way a pawn can get there is by shifting columns in capturing pieces. So it is rare that it happens.  

5.  The en-passing rule is the same as in two-player chess, and usually only occurs with pawns coming in laterally from the side players.  The test is also the same -- if the passing pawn (only on first move) could have been captured if only one move was made instead of two, the passed pawn may capture it on his next move.  If not taken on the first opportunity, en passing is forfeited.     

CHECK
A player may move his king into a check.  This is allowed because other players may intervene, deliberately or inadvertently, to block or cancel a check.  It is very risky to deliberately risk a check, because an ally may suddenly turn adversary, or not be successful in interceding.  As a courtesy, a player should be warned if he moves a king or queen into check.

CHECKMATE
On achieving a checkmate, the victorious player may not remove the vanquished king from the board until his next move, when he must actually capture the vanquished king.  This is necessary because the game does not necessarily end on a checkmate.  Allies and adversaries may interfere and rescue the checkmated king  -- attacking the victor's positions and  capturing or blocking a key attacking piece.

A player with a checkmated king may not move any of his pieces while his king is checkmated, and he must pass his turn while checkmated.   If  the checkmate is subsequently thwarted or neutralized by allies or adversaries, the rescued player may resume playing when his turn comes up again.  

When a king is captured and removed from the board, the defeated player's remaining pieces stay static on the board, but may be captured and removed by any remaining player. 

WINNING
1.   The last king remaining is the winner, assuming the victorious king also attacks and defeats his allies or adversaries. 

2.  When any two kings remain, they may declare an alliance and declare each other a winner.  More likely, however, is that old grudges will surface which cause the two remaining players to fight on.
    

Acquiring a four-player chess set

I don't currently sell a four-player chess set

There are a few ready-made four-player chess sets available. Just do a search on the internet, or on e-bay.  There are also custom fabricators who will build your board to order. 

If you are on a budget,  you can make your own board from this GIF image. 

The chess pieces are just ordinary chess pieces in different colors, including black and white.  You can buy a couple of cheap sets and paint them, or a plastic set and a wood set of approximately the same size.  

You may print out my rules and distribute them, providing you don't charge a fee for them, and you include the copyright.