Cannon shogi

Cannon shogi (大砲将棋 "taihō shōgi" cannon chess) is a modern variant of shogi (Japanese chess), however it is not Japanese. It was invented by Peter Michaelsen in February of 1998.

Rules of the game

Objective

The objective of the game is to capture your opponent's king.

Game equipment

Two players, Black and White (or 先手 "sente" and 後手 "gote"), play on a board ruled into a grid of 9 "ranks" (rows) by 9 "files" (columns). The squares are undifferentiated by marking or color.

Each player has a set of 20 wedge-shaped pieces, of slightly different sizes. From largest to smallest (most to least powerful) they are:

* 1 king
* 1 rook
* 1 bishop
* 1 gold cannon
* 1 silver cannon
* 1 copper cannon
* 1 iron cannon
* 2 gold generals
* 2 silver generals
* 2 knights
* 2 lances
* 5 pawns

Most of the English names were chosen to correspond to rough equivalents in Western chess, rather than as translations of the Japanese names.

Each piece has its name in the form of two kanji written on its face. On the reverse side of some pieces are two or three other characters, often in a different color (commonly red instead of black); this reverse side is turned up to indicate that the piece has been promoted during play. The pieces of the two sides do not differ in color, but instead each piece is shaped like a wedge, and faces forward, toward the opposing side. This shows who controls the piece during play. The game is often played with "Westernized" (or "international") pieces, which replace the kanji with more intuitive symbols, such as pictorial icons.

Table of pieces

Listed here are the pieces of the game and, if they promote, which pieces they promote to.

Each side places his pieces in the positions shown below, pointing toward the opponent.

* In the rank nearest the player:
** The king is placed in the center file.
** The two gold generals are placed in the adjacent files to the king.
** The two silver generals are placed adjacent to each gold general.
** The two knights are placed adjacent to each silver general.
** The two lances are placed in the corners, adjacent to each knight.

That is, the first rank is |L|N|S|G|K|G|S|N|L|.

* In the second rank, each player places:
** The gold cannon in the same file as the gold general on the player’s left.
** The silver cannon in the same file as the silver general on the player’s left.
** The iron cannon in the same file as the gold general on the player’s right.
** The copper cannon in the same file as the silver general on the player’s right.
** The bishop in the same file as the knight on the player's left.
** The rook in the same file as the knight on the player's right.
* In the third rank, the five pawns are placed in the same files as the lances, silver generals and king.

Game play

The players alternate making a move, with Black moving first. (The traditional terms 'black' and 'white' are used to differentiate the sides during discussion of the game, but are not literally descriptive.) A move consists of moving a single piece on the board and potentially "promoting" that piece, displacing ("capturing") an opposing piece or "dropping" a captured piece onto an empty square of the board. Each of these options is detailed below.

Movement and capture

An opposing piece is captured by "displacement": That is, if a piece moves to a square occupied by an opposing piece, the opposing piece is displaced and removed from the board. A piece cannot move to a square occupied by a friendly piece (meaning another piece controlled by the moving player).

Each piece on the game moves in a characteristic pattern. Pieces move either "orthogonally" (that is, forward, backward, left, or right, in the direction of one of the arms of a plus sign, +), or "diagonally" (in the direction of one of the arms of a multiplication sign, ×). The knight is an exception in that it does not move in a straight line.

Many pieces are capable of several kinds of movement, with the type of movement most often depending on the direction in which they move. The movement categories are:

tep movers

Some pieces move only one square at a time. (If a friendly piece occupies an adjacent square, the moving piece may not move in that direction; if an opposing piece is there, it may be displaced and captured.)

The step movers are the king, gold general, silver general, and the five pawns on either side.

Ranging pieces

The bishop and rook can move any number of empty squares along a straight line, limited only by the edge of the board. If an opposing piece intervenes, it may be captured by stopping at that square and removing it from the board. A ranging piece must stop where it captures, and cannot bypass a piece that is in its way. If a friendly piece intervenes, the moving piece is limited to a distance that stops short of the intervening piece; if the friendly piece is adjacent, it cannot move in that direction at all.

Jumping piece

The knight can "jump", that is, it can pass over any intervening piece, whether friend or foe, with no effect on either.

Cannon jump

The silver and iron cannons also jump, but more than that they "must" jump in order to move. That is, unlike the knight, these pieces cannot move unless the adjacent square in the direction they move is occupied, whether by friend or foe. That piece is unaffected by the jump, but any piece in the landing square is captured, just as with the knight.

They cannot capture a piece on an adjacent square until they promote.

Cannon ranging jump

The gold and copper cannons range like a rook and bishop, but like the other cannons they must jump in order to move. However, they may jump any number of pieces at any distance. They may capture where they stop. This differs from the cannons of xiangqi, which can only jump one piece, and which are only required to jump when they capture (indeed, xiangqi cannons may not jump "unless" they capture).

Promotion

A player's "promotion zone" consists of the three farthest ranks, at the original line of the opponent's pawns and beyond (that is, the opponent's territory at setup). If a piece "crosses" the board within the promotion zone, including moves into, out of, or wholly within the zone, but "not" including drops (see below), then that player may choose to "promote" the piece at the end of the turn. Promotion is effected by turning the piece over after it moves, revealing the name of its promoted rank.

Promoting a piece has the effect of changing how that piece moves until it is removed from the board. Each piece promotes as follows:

* A king or gold general cannot promote, nor can pieces which are already promoted.
* A silver general, knight, lance or pawn, when promoted, loses its normal movement and gains the movement of a gold general.
* A bishop or rook, when promoted, keeps its normal movement and gains the ability to move one square in any direction (like a king). This means the bishop is now able to reach any square on the board, given enough moves.
* The four cannons, when promoted, keep their normal movement and gain the ability to move one square in any direction (like a king).

If a piece that cannot retreat or move aside advances across the board until it can no longer move, it must be promoted. This applies to the pawn and lance, upon reaching the furthest rank, and to the knight upon reaching either of the two furthest ranks.

When captured, pieces lose their promoted status.

Individual pieces

Below are diagrams indicating each piece's movement. Pieces are pared with their promotion. Pieces with a grey heading start out in the game; those with a blue heading only appear on the board after promotion.

-! colspan="2" bgcolor="#e0e0e0" width="50%" | Rook! colspan="2" bgcolor="#d0d0f0" width="50%" | Dragon
-
Range: The rook can move any number of free squares along any of the four orthogonal directions.|
Range: The horse can move any number of free squares along any of the four diagonal directions.Step: It can move one square in any orthogonal direction.|
-! colspan="2" bgcolor="#e0e0e0" width="50%" | Silver Cannon! colspan="2" bgcolor="#d0d0f0" width="50%" | Promoted Silver Cannon
-
Cannon move/jump: The silver cannon can jump to the second square in one of the four orthogonal directions but only by jumping over another piece.|
Cannon move/range: The promoted copper cannon can move any number of squares along any of the four diagonal directions but must jump at least one piece in doing so.Step: It can step one square in any direction, orthogonal or diagonal.|
-! colspan="2" bgcolor="#e0e0e0" width="50%" | Gold General! colspan="2" width="50%" |
-
Step: The gold general can step one square in one of the four orthogonal directions; or,one square diagonally forward, giving it six possibilities.|
-! colspan="2" bgcolor="#e0e0e0" width="50%" | Knight! colspan="2" bgcolor="#d0d0f0" width="50%" | Promoted Knight
-
Jump: The knight jumps at an angle intermediate between orthogonal and diagonal, amounting to one square forward plus one square diagonally forward, in a single motion, ignoring any intervening piece. That is, it has a choice of two forward destinations. "A knight that reaches one of the two furthest ranks must promote."|
Step: The promoted lance can step one square in one of the four orthogonal directions; or,one square diagonally forward, giving it six possibilities.|

Drops

Captured pieces are truly "captured" in cannon shogi. They are retained "in hand", and can be brought back into play under the capturing player's control. On any turn, instead of moving a piece across the board, a player can take a piece he has previously captured and place it on any empty square, facing the opponent. The piece is now part of the forces controlled by that player. This is termed "dropping" the piece, or just a "drop".

A drop cannot capture a piece; that requires an additional move.

Pieces that are dropped in the promotion zone do not promote as a result: Promotion requires that piece make a normal movement on a subsequent turn, as detailed under "Promotion", above.

A pawn, knight, or lance may not be dropped on the furthest rank, since it would have no legal move on subsequent turns. Similarly, a knight may not be dropped on the penultimate rank.

There are two restrictions when dropping pawns:

A pawn cannot be dropped into the same file (vertical column) as another unpromoted pawn controlled by the same player. (A "tokin", or promoted pawn, does not count as a pawn when considering this drop restriction.) A player who has an unpromoted pawn on every file is therefore unable to drop a pawn anywhere. For this reason, it is common to sacrifice a pawn in order to gain flexibility for drops.

A pawn cannot be dropped directly in front of the opponent's king, if the opponent would have no way to prevent his king being captured on the next move. In other words, a pawn cannot be dropped to give immediate mate.

It is very common for players to swap bishops, which face each other across the board. This leaves each player with a bishop "in hand" to be dropped later, and gives an advantage to the player with the stronger defensive position.

Check and mate

When a player makes a move such that the opponent's king could be captured on the following move, the move is said to "give check" to the king; the king is said to be "in check". If a player's king is in check and no legal move by that player will get the king out of check, the checking move is also "mate", and effectively wins the game.

A player is not allowed to give perpetual check.

Game end

A player who captures the opponent's king wins the game. In practice this rarely happens, as a player will resign when checkmated, as otherwise when loss is inevitable.

A player who makes an illegal move loses immediately. (This rule may be relaxed in casual games.)

There are two other possible (but fairly uncommon) ways for a game to end: repetition (千日手 "sennichite") and impasse (持将棋 "jishōgi").

If the same position occurs four times with the same player to play, then the game is no contest. (Recall, however, the prohibition against perpetual check.) For two positions to be considered the same, the pieces in hand must be the same, as well as the position on the board.

The game reaches an impasse if both kings have advanced into their respective promotion zones and neither player can hope to mate the other or to gain any further material. If this happens then the winner is decided as follows: each rook, bishop and cannon scores 5 points for the owning player, and all other pieces (except kings) score 1 point each. Promotions are ignored for the purposes of scoring. A player scoring less than 38 points loses. If both players have at least 38 points, then the game is no contest.

Games which are no contest are usually counted as draws in amateur tournaments, but in professional style tournaments the rules typically require the game to be replayed with colors reversed (possibly with reduced time limits).

Handicaps

Games between players of disparate strength are often played with handicaps. In a handicap game, one or more of White's pieces is removed before the start of play, and White plays the first move of the game. Note that the pieces removed at the beginning play no further part in the game - they are not available for drops. The imbalance created by this method of handicapping is not as strong as it is in chess, because material advantage is not as powerful in shogi as in chess.

Common handicaps, in increasing order of size, are as follows:
*Remove White's left lance
*Remove White's bishop
*Remove White's rook
*Remove White's rook and left lance
*Two pieces: remove White's rook and bishop
*Four pieces: remove White's rook, bishop and both lances
*Six pieces: remove White's rook, bishop, both lances and both knights

Other handicaps are also occasionally used. The relationship between handicaps and differences in rank is not universally agreed upon; several different systems are in use.

Game notation

The method used in English-language texts to express shogi moves was established by George Hodges in 1976. It is derived from the algebraic notation used for chess, but differs in several respects.

A typical example is P-8f.The first letter represents the piece moved: P = pawn, L = lance, N = knight, S = silver, G = gold, GC = gold cannon, SC = silver cannon, IC = iron cannon, CC = copper cannon, B = bishop, R = rook, K = king.Promoted pieces have a + added in front of the letter. e.g., +P for a tokin (promoted pawn).The designation of the piece is followed by a symbol indicating the type of move: - for an ordinary move, x for a capture, or * for a drop.Next is the designation for the square on which the piece lands.This consists of a number representing the file and a lowercase letter representing the rank, with 1a being the top right corner (as seen from Black's point of view) and 9i being the bottom left corner.(This method of designating squares is based on Japanese convention, which, however, uses Japanese numerals instead of letters. For example, the square 2c is denoted by 2三 in Japanese.)

If a move entitles the player to promote the piece, then a + is added to the end to signify that the promotion was taken, or an = to indicate that it was declined.For example, Nx7c= indicates a knight capturing on 7c without promoting.

In cases where the above notation would be ambiguous, the designation of the start square is added after the designation for the piece in order to make clear which piece is meant.

Moves are commonly numbered as in chess.

In handicap games White plays first, so Black's move 1 is replaced by an ellipsis.

Strategy and tactics

Drops are the most serious departure from Western chess. They entail a different strategy, with a strong defensive position being much more important. A quick offense will leave a player's home territory open to drop attacks as soon as pieces are exchanged. Because pawns attack head on, and cannot defend each other, they tend to be lost early in the game, providing ammunition for such attacks. Dropping a pawn behind enemy lines, promoting, and dropping a second pawn behind it so they protect each other is a strong attack; it threatens the opponent's entire defense, but provides little of value if the attack fails and the pieces are captured.

Players raised on Western chess often make poor use of drops, and dropping is half the game. If a player has more than a couple captured pieces in hand, it is likely that dropping attacks are being overlooked. However, it is wise to keep a pawn in hand, and often to exchange pieces if necessary to get one.

A decision made early in the game will be whether or not to exchange bishops. If exchanged, it may be possible to drop a bishop behind poorly defended enemy territory for a "fork" attack, threatening two vital pieces at once. (Silvers are also commonly used this way.) Even if such a bishop merely retreats, it may promote in doing so, and a promoted bishop can dominate the board.

However, attacking pieces can easily become trapped behind enemy lines, as the opponent can often drop a pawn in a protected square to cut off a line of retreat. For this reason, rooks are commonly kept at a safe distance in the early parts of the game, and are used to support attacks by weaker pieces.

Many common attacks involve advancing a silver general along a file protected by the rook. Because silvers have more possibilities for retreat, while golds protect pieces at their sides, silver generals are generally considered superior as attacking pieces and gold generals superior as defensive pieces.

Advancing a lance pawn can open up the side of the board for attack. Therefore, when a player first advances a lance pawn, it is usual for the opponent to answer by advancing the opposing pawn, in order to avoid complications later in the game.

Because defense is so important, and because shogi pieces are relatively slow movers, the opening game tends to be much longer than in Western chess, with a dozen or so moves of shoring up defenses before any attack is made.

See also

* Shogi variant
* Whale shogi
* Minishogi
* Judkins shogi
* Microshogi
* Kyoto shogi
* Yari shogi

External links

* [http://www.chessvariants.org/shogivariants.dir/cannonshogi.html Shogi: Cannon Shogi]