Decimaka (revised)
Decimaka is a western Chess variant that tries to emulate the promotion dynamics of the historic Japenese Chess game 'Maka Dai Dai Shogi'. In particular, promotion is not reserved for Pawns. Most piece types from the initial setup can promote, and the right to promote originates from making a capture, rather than reaching a promotion zone. So promotion can happen everywhere on the board.
This makes tactics highly non-trivial. It also impacts strategy, because promotion at the end of a game is not automatic, and in fact impossible if the opponent would not have any easy targets for capturing.
The original version of this game was published in 2018. Since then it has become clear (also through experience with the smaller variant Veteran Chess, which uses the similar promotion rules) that this original design has some flaws. The game was very static, because trading of Pawns protected by Pawns was strongly discouraged by the fact that this would result in a promotion in the recapture. In Shogi variants that was not a problem, as Pawns can never protect each other there. In addition too many games would end without a Queen ever appearing, because the Fiancees were traded out of the game before they could promote. Now that I am correcting these flaws, it is a good opportunity to alter a few other details too. The rule changes are written in italics.
Setup
Pieces
- King - moves as orthodox King. Takes 3 steps towards Rook on castling
- Queen (promoted Fiancee) - moves as orthodox Queen
- Lion - Moves as King, Knight or jumps 2 squares orthogonally or diagonally
- Star - Jumps one, two or three squares orthogonally or diagonally
- Berserker(promoted Lion)- Moves like a Lion, or slides up to three squares orthogonally or diagonally
- Trident (promoted Tee) - slides along files, or diagonally forward
- Nightrider (promoted Knight) - makes arbitrarily many Knight moves in the same direction, until blocked
- Rook - moves like orthodox Rook
- Bishop - moves like orthodox Bishop
- Knight - moves like orthodox Knight
- Fiancee - moves like orthodox King (but is not royal)
- Y - slides forward diagonally or backwards along a file, both maximally 3 squares
- Cross - steps one or jumps two squares in all orthogonal directions
- Tee - steps one square straight forward or backward, or diagonally forward
- Omni (promoted Pawn, Cross, Y, Star or Lion) - captures one step diagonally, moves without capturing one step orthogonally
- Pawn - moves like orthodox Pawn, including a double push from its initial location, and e.p. capture
Rules
The game is won by checkmating the opponent King. Stalemate is a draw.
Pieces can (and sometimes must) promote when they make a capture. This can happen anywhere on the board, there isn't any special promotion zone. Promotion is mandatory when you capture a promoted piece; otherwise it is optional, and you can choose not to promote.
Pawns cannot promote by capturing other Pawns, though.
A piece other than King which captures a Queen or a Fiancee promotes to Queen in the same turn. That also applies to pieces that are already promoted, or would normally not promote at all.
Pawns that reach the final rank are stuck there like dead wood.
Notes
There are four classes of pieces, depending on how they promote:
- Unpromotable pieces (King, Rook, Bishop).
- Pieces that turn from steppers/leapers into the corresponding sliders/riders (Fiancee, Knight, Tee).
- Pieces that promote to Omni (Star, Y, Cross, Pawn). Which, for all but the latter, is actually a demotion.
- The Lion is in a class of its own, and promotes to the even stronger Berserker.
Promotability has a huge affect on tactics. Where without it an exchange typically is most profitable whan you capture with the least-valuable piece first, with it you would try to end with the piece that has the best promotion. Furthermore, when you won't make the last capture yourself, you can sometimes try to discourage the opponent's recapture by promoting (if he can only recapture with a strongly demoting piece). Which is a reason to order unpromotable pieces earlier, even when they are more valuable.
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By H. G. Muller.
Last revised by H. G. Muller.
Web page created: 2022-04-28. Web page last updated: 2022-04-28