Minjiku Shogi

Minjiku Shogi is a variant in the spirit of the 17th-century Japanese game Tenjiku Shogi, but on a much smaller board (10x10 instead of 16x16). In still qualifies as a large variant: each player starts with 32 pieces of 17 different types, many of which can promote, sometimes to pieces of a type not originally present.

The iconic pieces in Tenjiku Shogi, which give that variant its unique flavor, and dominate the opening play, are the Fire Demons and the jumping generals. The Fire Demons capture ('burn') every enemy piece in the 3x3 area surrounding their location, even passively during the opponent's turn. The jumping generals can hop over arbitrary many pieces for capturing or checking, which makes smothered checkmates a major opening theme, as the King starts so deeply buried in its own camp that it takes a long time to provide any 'breathing space' for it. Minjiku Shogi is an attempt to preserve this game dynamics as much as possible in a much smaller game, by eliminating the host of weak pieces that are almost never touched in Tenjiku Shogi.

Many of the original Tenjiku pieces were perceived as too powerful for a mere 10x10 board, however. So Minjiku Shogi is designed with novel pieces, often never seen before, which can be viewed as 'caricatures' of their original Tenjiku-Shogi counterparts: they still have the capabilities that are characteristic for these originals, but often in a more modest amount. E.g. where some of the pieces in Tenjiku Shogi can make 'area moves' consisting of three independent King steps, this is reduced to two steps in Minjiku Shogi. And where the Tenjiku Fire Demon burns its eight neigbors, the Minjiku Fire Dragon only burns the four diagonally adjacent ones.

Setup

Pieces

Pieces can always capture in the same way as they could move to empty squares, but some pieces have additional 'capture-only' moves:

• Fire Dragons capture all diagonally adjacent enemies as an automatic side effect of their move. This happens in addition to any ordinary capture they might make with that move.
• The jumpers can capture behind obstacles in their path. They are not always able to hop over each other, though. There is a ranking for them (which also includes the King), and they cannot hop over pieces of equal or higher rank. (This applies to friendly as well as enemy pieces!) The ranking is:
  King > Jumping General > Area Jumper > Orthogonal Jumper = Diagonal Jumper > any other piece.
• Several pieces can capture adjacent enemies without moving. This does take a turn, in which one of the adjacent enemy pieces is simply removed from the board.

Some pieces can make an 'area move' consisting of up to two King steps. The directions of these steps can be chosen independently. The second step is only allowed if the first went to an empty square, so it is not possible to capture two pieces in one move by this. Effectively passing a turn by returning to the square it came from is not allowed.

The Ninja has a 'ski-slide', which ignores the first square in that direction (whether it is empty or occupied), and starts sliding from the second square instead.

	pawn	steps one square straight ahead	promotes to gold
	silver	steps one square diagonally, or straight ahead	promotes to bishop
	gold	steps one square orthogonally, or diagonally forward	promotes to rook
	minister	steps one square in all 8 directions	promotes to orthogonal jumper
	kirin	steps one square diagonally, or jumps to the 2nd square orthogonally	promotes to samurai
	phoenix	steps one square orthogonally, or jumps to the 2nd square diagonally	promotes to queen
	lateral mover	slides sideways, or steps one square forward or backward. When it first moves it can also slide two squares forward, also to capture	promotes to ninja
	bishop	slides diagonally	promotes to viper
	rook	slides orthogonally	promotes to cobra
	diagonal jumper	slides diagonally, and can jump over arbitrary many pieces on the diagonal for capturing the piece in the square it lands on	promotes to lion
	viper	slides diagonally, or captures an orthogonally adjacent enemy without moving	promotes to area jumper
	cobra	slides orthogonally, or captures an diagonally adjacent enemy without moving	promotes to jumping general
	queen	slides in all 8 directions	promotes to fire dragon
	orthogonal jumper	slides orthogonally, and can jump over arbitrary many pieces on the file or rank for capturing the piece in the square it lands on	Only available as a promoted minister, so cannot promote again
	samurai	makes a knight's jump, or captures an adjacent piece without moving	Only available as a promoted kirin, so cannot promote again
	ninja	steps one square diagonally, or leaps to the second square sideways, from where it can go on sliding outward. In addition it can capture an orthogonally adjacent enemy without moving.	Only available as a promoted lateral mover, so cannot promote again
	lion	can make an area move (see above)	Only available as a promoted diagonal jumper, so cannot promote again
	area jumper	slides diagonally, and can jump over arbitrary many pieces on that diagonal for capturing. In addition it can make an area move (see above).	The area jumper cannot promote
	jumping general	slides in all 8 directions, and can jump over arbitrary many pieces in its path for capturing the piece in the square it lands on	The jumping general cannot promote
	fire dragon	slides in all 8 directions. In addition it can make an area move (see above). Burns all enemies diagonally adjacent to its destination on all these moves, if it doesn't get burned itself (see below)	The fire dragon cannot promote
	king	steps one square in all 8 directions	The king cannot promote

Rules

Fire Dragons also burn passively: pieces arriving on a square diagonally adjacent to an enemy Dragon during their own move disappear (but still capture the piece in the destination). This is automatic, and and doesn't count as a move of the player who's Dragon does the burning. It even applies to a moving Fire Dragon itself, and in this case the moving Dragon will not burn any of its own neighbors when it gets burned.

The squares on which the King and Minister start are so-called 'brouhaha squares': they disappear as soon as they are evacuated. It is possible to capture a piece that stands on such a square, though, which implies a King can be in check there.

Most pieces in the initial array can promote, and optionally do so when entering the enemy camp (the furthest three ranks, not counting the brouhaha squares), or when making a capture starting in that camp. (So not when they leave, or move entirely inside the camp without capturing!) There is no choice for what to promote to; each piece has its own designated promoted form. When a piece is promoted, it will keep the new move for the rest of the game; it can never revert to its original move, and it can never promote a second time, even when pieces with the same move that were originally present are promotable.

The goal is to checkmate the enemy King.

Perpetual checking is forbidden: if on the third occurrence of a position all moves of one player since the previous occurrence delivered check, the player delivering those checks loses.

Otherwise three-fold repetition is a draw.

After 50 moves without capture or promotion the game ends in a draw. (Note that other moves of Pawns or other promotable pieces do not reset the counter.)

When a Queen promotes to Fire Dragon this burns the diagonally adjacent enemies like the Dragon would.

Notes

After 1.g4 black immediately faces a mate threat (2. Jj6#), which can only be defended against through 1... Yi7 or 1... j7 (2. Axj7 Lxj7).

The Chu-Shogi Lion was considered too strong a piece for this variant, and its absense eliminated all 'hit-and-run captures' from Minjiku Shogi. The 'capture without moving' (a.k.a. rifle capture or igui) was retained, though. In Tenjiku Shogi this capture mode occurs with the Horned Falcon, Soaring Eagle, Lion, Lion Hawk, Free Eagle and the promotion piece Heavenly Tetrarch. Minjiku Shogi kept it in the array pieces Viper and Cobra, which can be considered caricatures of the Free Eagle and Lion Hawk, repectively (as these also are sliders). The Samurai can be considered a caricature of the Lion. (Hence the Kirin promotes to it.)

The Ninja is a caricature of Tenjiku's Heavenly Tetrarch: it has a ski-slide in combination with rifle capture on the adjacent square.

The Orthogonal Jumper is identical to Tenjiku's Rook General (the names of these jumping generals were altered to get more convenient one-letter IDs for the pieces). It was not included in the initial array because it doesn't play such an important role even in Tenjiku Shogi: in the symmetric setup they face each other, and usually get traded at the first opportunity, to prevent one player can do something useful with it. And of course some pieces have to be eliminated when there is room for only 22 non-pawns, instead of 60. It did make a convenient promotion piece for the Minister, though. (Which is stronger than Gold, so that it would be illogical for it to have a promotion to something weaker than Rook, if we wanted to retain the usual G->R promotion. Which was why I discarded the Lateral Mover as the promotion piece.)

The King starts on a brouhaha square to better mimic the extreme difficulty in Tenjiku Shogi to avert smothered mates. With only a single rank of pieces and one filled with pawns in front of it, this would become much too easy, while adding extra board ranks would be at odds with the goal of making a relatively small game. The advantage a brouhaha square offers in this respect is that creating a single adjacent hole for the King is not sufficient, as the King could then suffer a smothered checkmate there, where there otherwise would only be a perpetual where the King could evade the check by returning to the square it came from.

The Viper, Cobra, Samurai and Ninja have moves that were conceived specifically for this variant, and to my knowledge were never used before in other chess or shogi variants.

The rule that promotion to Fire Dragon already burns adjacent enemies is most likely how historic Tenjiku Shogi was played, which differs in this respect from the 'Modern Tenjiku Shogi' rules.

Last revised by A. M. DeWitt.