A lot of the strategic concepts that can be found in regular chess also apply to four-player chess. However, there are also key differences. This section covers the strategic ideas that are part of four-player chess. Each of the two main variants (Teams and FFA) is covered separately, as they are very different.
As for all team games, working together as a team is a really important part of the Teams variant of four-player chess. This is true for both attacking and defending. Proper attack and defence strategies require good coordination between both teammates to be successful. A better coordinated team will usually beat a less coordinated team. It is also important to note that two heads are usually better than one. If one player merely follows his teammate's suggested moves, their level of play can only be as good as that single player. If two teammates work together properly and exchange ideas, they can surpass their individual skill levels by complementing each other's strengths and perform at a higher level together.
Just like in regular chess, development of pieces is very important. This involves moving pieces to their most active squares, controlling key squares on the board and trying to interfere with the opponents' development.
Bringing out the queens
An important difference with regular chess is that bringing the queen out early can be very strong in four-player chess and may often be a good idea. The four-player chess board is significantly larger than a regular chess board and therefore the queens are not as vulnerable to tempo moves as in regular chess. The queens are also very good at controlling key squares on the board and creating multiple threats, because of their great mobility. However, a mistake commonly made by less experienced players is to keep moving the queens around in the opening only to create one-move threats that are easily parried, while their opponents gain a significant lead in development.
Bishops versus rooks
In the opening phase of the game, the bishops are generally considered slightly stronger than the rooks. The bishops can create direct threats against the opponents on both sides of the board using the long diagonals, whereas rooks need to move to the centre of the board first. Moreover, developing the rooks is inherently more difficult, because opponents can push their rook pawns or develop their knights to block the rooks and prevent them from moving out. Rooks are also sometimes used as bait to distract and temporarily trap enemy queens in exchange for a strong (checkmating) attack. As the game progresses and moves towards the endgame, however, the rooks become more important. It is much easier to checkmate opponents with rooks rather than bishops. In general, the team with active rooks usually has the better winning chances in the endgame. Therefore, it is often best to avoid unnecessarily capturing pawns and creating openings in the opponents' pawn structures. Instead, the files and ranks should be kept closed to hinder the opponents' rook development and any open files and ranks should be blocked (with pawns), such that the rooks remain trapped behind the wall of pawns and cannot easily come into play.
Since the four-player chess board is significantly larger than a regular chess board, the difference in mobility between the sliding pieces and the knights is also more pronounced. Knights are not often found in the centre of the board. They usually control the corners of the board and they are often used to create check threats, defend against enemy knights or simply block check lines for protection of the king. The main strength of the knights is that knight checks cannot be blocked. That makes them very strong pieces once they get in range of an enemy king. Knights are often sacrificed to get a check on an opponent, either for a strong attack or for defensive purposes.
Mobility and space
Because of the larger board size and the more tactical nature of four-player chess, the positional concepts of piece mobility and spatial advantages are less relevant to four-player chess. However, players can still be forced into a cramped position by active piece play from opponents and the risk of overextension is also present in four-player chess. Pushing pawns too far up the board may seriously weaken the king's position, possibly even more so than in regular chess.
Centre and corners
Unlike in regular chess, the centre of the board cannot be controlled by pawns (because it is further away), but it can be controlled by pieces and it is just as important. The team that controls the centre of the board normally has the initiative and can more easily create threats and start attacks. In four-player chess the corners are also key areas of the board, because that is where the opposing armies meet directly. The corners can be controlled by pawns and often the rook pawns are pushed two squares forward to control or attack the opponent's knight and to block the opponent's rook.
In four-player chess it is generally not wise to castle in the opening phase or middle game. The king is usually safest in the centre, surrounded by supporting pieces. Castling brings the king closer to the enemy and actually weakens the king's position considerably. The weak pawn shield covering the king will immediately become a target. On the side of the board the king only has defending pieces on one side, whereas in the centre the king has supporting pieces on both sides. As pieces are exchanged and the game reaches the endgame, it may be safe to castle to develop the rook, if necessary. However, even then it may be preferable to keep the king in the centre and just move it up one square. In the end a centralised king is important to support the pawns, when pushing for promotion.
The importance of squares
The weakest squares
Just like in regular chess, each side has an inherently weak square in the starting position that is only protected by the king. For Red this is the i2 square, for Blue the b9 square, for Yellow the f13 square and for Green the m6 square. These squares often become a target for attack, particularly in the opening phase of the game. Players need to be very wary of attacks aimed at these vulnerable squares. Since castling is generally ill-advised, these squares may remain vulnerable throughout the game.
Other potential weaknesses are the squares that are only guarded by the queens: f2, b6, i13 and m9 for Red, Blue, Yellow and Green, respectively. If the queens are developed early, these squares may be left undefended and could become a point of infiltration for enemy queens. However, it is not always a good idea to grab the pawns on these squares and one should think twice before doing so. If there is no strong follow-up, it only makes it easier for the opponent to get the rook(s) into the game later on, which can be a significant advantage. Sometimes players may intentionally leave these pawns unprotected to tempt the opponents to take them.
Squared guarded only by bishops are weakness too. Often, if bishop goes out, players need to move d3 or k3. But if fianchetto is done, this square is defended.
Often players push the rook pawns two squares to attack or defend against enemy knights. However, this does come at a cost. Pushing the pawn means the adjacent square on the opponent's side can no longer be protected by a pawn and becomes a weakness. Usually if a player does this on the queenside, the opponent simply develops the knight to the edge of the board, occupying the weak square. This is a nice outpost for the knight, as it cannot be kicked by a pawn and it can hop in to attack the enemy rook if an opportunity arises. Moreover, the knight then defends the potentially weak f2, b6, i13 or m9 square.
It is generally a bad idea to to advance pawns hoping to queen them in teams. This is generally for two major reasons.
The first is that pawns take longer to promote in teams (the 11th rank as opposed to the 8th rank for FFA). Pushing pawns to queen risks over extending your self. Further, your partner can inadvertantly kill your dreams of promotion, as your promotion rank is really close to your partner. Your partner has to advance their pawns only two squares to make your pawn rush nearly worthless.
The second major reason is that this slows development. A good team can punish both you or your partner while you're only advancing pawns.
It is generally advisable in the four-player chess FFA variant to develop pieces relatively quickly. This is normally done in the beginning of the game, though many players do a pawn rush and/or castle before they develop all pieces. Players develop by getting their bishops and knights off the back row, sometimes fianchettoing the bishop, to avoid them getting in the way and negatively affecting rooks and queens. Another way they can do this is by moving their pawns forward, which can affect an opposing player's development and give the major pieces even more space to move around.
A pawn rush is when players run a pawn (or pawns) to the centre of the board, attempting to get a queen. One method is, at the beginning of the game, to rush one pawn, often the queen pawn, out, hoping to get a queen. If other players do not stop the pawn, it can queen, and that player can then develop and/or castle. Players can also castle and/or develop and then attempt to get a queen, though players may have a harder time at this point to do so, as opponents may have gotten a queen or are more prepared to stop a potential queen. Another method is to move along with two or more pawns and go to the centre, hoping that the combined pawns may be able to get one or more queens. Finally, if a player to the side of you is out of the game, one can try to move a side pawn(s), which will face little or no resistance as that player that would originally block it is gone. All these should be experimented with, in order to determine one's best strategy.
Some FFA players believe that it is dangerous to have their opposite player gone and be stuck between two side players. Some choose, therefore, to work with their opposite to checkmate a side player. If both players cooperate, then they can attack a certain player together or one attacks and the other fends off the opposite of the player who is being attacked. They often try to prevent the other opponents from getting a queen, only allowing their own opposite to get a queen. Sometimes opposites even refuse to take each other's pieces. If all four players help their opposite, then it can become much like a team game, though they are forbidden to communicate with each other. This strategy is typically only seen in higher level play.