Tengu Dai Shogi

Recently I encountered a description of a new large Shogi variant at this link. It appears to be a modernized version of Dai Shogi, where some of the weak pieces that the latter had in addition to the piece set from Chu Shogi are replaced by strong pieces from Dai Dai Shogi (and in some cases not-so-strong pieces from Tai Shogi). Unlike Dai Shogi, but similar to Chu Shogi, it has rules to prevent quick trading of the strongest pieces. The name is derived from the strongest participating piece, the Tengu (a.k.a. Long-Nosed Goblin), which is a diagonal hook mover. It looks like a quite interesting game.

Compared to Cashew Shogi, another mid-size variant (13x13) that uses pieces from Dai Dai Shogi, Tengu Dai Shogi much more resembles Dai Shogi. It doesn't have the mandatory-promotion-on-capture rule of Dai Dai Shogi, but promotions work exactly as in Dai Shogi: optionally on entering the enemy camp. And promotion is almost always to the same type as in Dai Shogi, while in Dai Dai Shogi promotions can be quite different or absent.

Setup

Each piece's powers of movement are briefly described in parentheses using Betza notation. To see a diagram of how the piece moves, click on the piece name. To see the piece it promotes to and a diagram of how that piece moves, click it again. Written explanations of the more complicated pieces are given in the Pieces section, and a list of what each piece promotes to is given in the Rules section.

Pieces

Most Shogi pieces can be described as orthodox Queens with range limits in some or all of the eight directions. The possible ranges in this variant are infinite (i.e. no limit), 3, 2, 1 (just a step, like king) or 0 (meaning it doesn't move in that direction at all), and different directions (even those related by symmetry) can have different range. The mnemonic representation reveals how such pieces moves; basically the shape of the piece is its move diagram: an 'inner' square represents the King moves (range 1), and 'bites' taken out of it indicate the directions in which it cannot move at all. Longer ranges are indicated by an outward 'bulge'. A radial line drawn on the piece in that direction then indicates infinite range, a dot near the tip range 3, and no markings at all range 2.

Mnemonic piece symbol

Tengu

The Tengu is a diagonal hook mover. That is, it slides like a Bishop, but is allowed to make a 90-degree corner on any empty square a Bishop could reach, and continue as a Bishop from there. On an empty board this would make it attack all squares of the shade it is on, which makes it an enormously powerful piece. And additional orthogonal step move lifts the color binding.

Lion

The Lion is a double mover: it can make upto 2 King steps per turn, changing direction between them, even when this returns them to their starting square. They can make the first step as jump, when it choose to do so. So it can:

• Jump directly to any square in the 5x5 area surrounding it,
• Annihilate any opponent standing next to it, without moving (formally one step, and then a step back),
• Annihilate any opponent standing next to it, moving on to an empty square next to that ('hit and run'),
• Annihilate any opponent standing next to it, and normally capture an opponent standing next to that ('double capture'),
• Stay in place without capturing anything if one of the neighboring squares is empty (effectively passing a turn)

Lion Dog

The Lion Dog appears here in its most powerful version, of a linear 3-step mover with full lion power. That means it can move up to three steps along any of 8 rays, possibly reversing direction at any point (but not overshooting its starting square), and (optionally) capture or hop over whatever was in the squares it visits this way. So it does not have to terminate its move after a capture, and can capture up to 3 pieces in one turn. In summary, the Lion Dog can:

• Directly leap to one of the first three squares in any direction, possibly capturing what was there,
• Leap to the 3rd square in any direction, possibly capturing what was there, and annihilate enemies on the 1st and/or 2nd square,
• Leap to the 2nd square, possibly capturing what was there, and annihilate an enemy on the square it jumped over,
• Step to an adjacent square, possibly capturing what was there, and annihilate an enemy on the 2nd square in that direction,
• Annihilate an adjacent enemy without moving,
• Step back and forth to an empty adjacent square, effectively passing a turn.

Its most dangerous move is probably a "2-out-1-in" capture, with which it can attack a protected piece from a safe distance, and doesn't stay at the capture square to be recaptured after taking it.

Furious Fiend

The Lion promotes to Furious Fiend, which can move as Lion or Lion Dog. Many of the Lion Dog moves already occurred in the Lion, but those that end on the third square, and '2-out-1-in' are very valuable additions, which make the Furious Fiend an immensely powerful piece.

Soaring Eagle, Horned Falcon

Eagle and Falcon move as Queen, except that in some directions they do not slide, but have a 'stinging' move, which can:

• Move to the first or jump to the second square,
• Jump to the second square, annihilating an opponent on the first square,
• Annihilate an opponent on the first square without moving (formally one step, and then a step back),
• When the first square is empty, move there and step back (effectively passing the turn).

They can do any of this while capturing an opponent on the final square, or when moving to an empty square. The Horned Falcon does this only straight forward, the Soaring Eagle in the two diagonally forward directions.

Crown Prince

The Elephant promotes to Crown Prince, which is just another name for King. So you can have two royals in Dai Shogi. This counts as extinction royalty, i.e. when you have two royals, one of them can be captured without ill effects, and only when your last royal is captured you lose the game.

Knight

The Knight is an orthodox Chess Knight, rather than its Shogi version. Upon promoting to Stallion, it gains the move of the Gold General.

Pawn

The Pawn occurs in the Shogi version, moving and capturing straight ahead.

Rules

Goal

The game is won by eliminating the opponent's royal piece(s). Royal are King and 'Prince', the latter being a second King obtainable through promotion. There is no rule against venturing into or leaving yourself in check, although this would of course be unwise. This makes stalemate non-existent in real games. For definiteness we can assume that stalemate is a win.

Anti-trading rules

Lions and Lion Dogs cannot capture Lions or Lion Dogs when they could be recaptured immediately. One assumes that this also holds for Lions and Lion Dogs that were obtained by promotion (of Kirin or Phoenix). This is a rule similar to that in Chu Shogi, except that it is extended here to also apply to Lion Dogs. The 'counterstrike rule' of Chu Shogi, which forbids indirect Lion trading there, does not apply in Tengu Dai Shogi. After promotion the Lion loses its protection from trading. (?)

The Tengu cannot capture each other in any circumstances.

Promotion

Like in most Shogi variants, it is not just the Pawns that can promote, but almost all pieces. There is no choice for what to promote to: each piece type has a pre-determined promoted form (written on the back of the tile used to represent the piece, so that it can be flipped to perform the promotion). They often promote to a piece that was already present in the initial setup. But in that case it cannot promote again, even if the latter does: every piece promotes at most once. So a Rook obtained by promoting a Gold is really a different Rook from the one present initially, as the latter can still promote, and is thus much more valuable.

Pieces can promote when they enter the promotion zone formed by the furthest five board ranks. This is optional; you can always defer promotion, and in some cases that makes sense, because not all promoted pieces are strictly upward compatible with their unpromoted forms. In addition, moves that start inside the promotion zone provide an opportunity to promote when they capture something.

Pieces promote as follows (moves only indicated for pieces not occurring in the initial setup):

Kirin -> Lion Phoenix -> Lion Dog Lion -> Furious Fiend (Lion + Lion Dog) Dragon King -> Soaring Eagle Rook -> Dragon King Gold General -> Rook Pawn -> Gold Dragon Horse -> Horned Falcon Bishop -> Dragon Horse Ferocious Leopard -> Bishop Vertical Mover -> Flying Ox (BvR) Silver General -> Vertical Mover Lance -> White Horse (vRfB) Reverse Chariot -> Whale (vRbB) Blind Tiger -> Flying Stag (vRFsW) Drunk Elephant -> Crown Prince (royal K) Go Between -> Drunk Elephant Side Mover -> Free Boar (BsR) Copper General -> Side Mover Knight -> Gold General Evil Wolf -> Gold General Violent Ox -> Gold General Flying Dragon -> Gold General

One army with all pieces promoted

Repetitions

One assumes that the rules concerning repetition are the same as in modern Chu Shogi: check evasions and moves that do not create any new attacks are always allowed, other moves that create a position that occurred before not. Except for turn passing, where the player that passed first must deviate.

Notes

The Vermillion Sparrow and Turtle-Snake are pieces from Tai Shogi, but they move somewhat differently here than either the English or Japanese description of their move there (which are quite different), or the move they are said to have in Taikyoku Shogi (which is similar to the Japanese Tai-Shogi move). They still conform to the Japanese idea that these are asymmetric pieces that slide along a single diagonal, and they are each other's mirror image.

The Great Dragon slightly different from what it does in Dai Dai Shogi (where it is the 90-degree rotated version of the Golden Bird): instead of the diagonal forward range-3 slide, it has sideway jumps to the second and third square. This is the description the Japanese Wikipedia gives for the primordial Great Dragon in Tai Shogi. But not for the Great Dragon obtained by promotion of a Kirin there, so likely erroneous. Tengu Dai Shogi has taken this move, however.

The Phoenix is the only piece that has its promotion altered compared to Dai Shogi: it promotes to Lion Dog instead of Queen. The Lion, which does not promote in Dai Shogi, now promotes to Furious Fiend (as it does in Dai Dai Shogi).

Four pairs of pieces (all promoting to Gold) were removed from Dai Shogi to make room for the new pieces in this variant: Cat Sword, Angry Boar, Iron General and Stone General. These were replaced by 8 new 'singletons' (to import some of the asymmetric character of Dai Dai Shogi), none of which promotes.

The start location of the White Tiger and Blue Dragon is a bit surprising, as their diagonal slides aim towards the board edge rather than towards the center. In Dai Dai Shogi this is the other way around: the Blue Dragon starts on the left.

Last revised by A. M. DeWitt.