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This item is a game information page
It belongs to categories: Orthodox chess, 
It was last modified on: 2002-11-01
 By Mark  Thompson. Tetrahedral Chess. Three dimensional variant with board in form of tetrahedron. (x7, Cells: 84) [All Comments] [Add Comment or Rating]
Charles Gilman wrote on 2004-01-06 UTC
Having analysed this arrangement of cells I have worked out the distances between cells. Below is a sample of square roots of distances from the cell marked 0 on alternate layers of 6x5 and 5x6, shown as digits in base 36 (A=10, B=11,... Z=35). Thus moves can be traced for Rook (0149G... same or successive levels), Bishop (028I... same or alternate levels), Unicorn (03C... successive or alternate levels), and Nightrider (05K... same or successive levels). Note however that the 9 on the level adjoining the starting one is NOT part of a Rook move, but a coprime move like 2:2:1 on a cubic-cell board. Note also that the number 7 represents exactly the commonest oblique piece of hexagonal-cell variants. 2125AH 3359F 10149G 1137D 4347CJ 779DJ 2125AH 1137D 3236BI 557BH A9ADIO 5458DK 3359F 4347CJ 557BH 989CHN A9ADIP 779DJ 747AFM 779DJ A9ADIO DDFJP CBCFKR BBDHN DCDGLR HHJNT IHILQW

Charles Gilman wrote on 2003-06-28 UTC
The problem with your idea of reducing the colours to two is that four colours really do reflect best the real relationship between the squares, as the rotations in my previous comment illustrate. In a game that does not use the diagonal move it makes sense for two of the Pawn's orthogonal moves to be capturing and two non-capturing, but which are which is entirely arbitrary. Associating one pair of these moves with the orthogonal same-level move and the other pair with the diagonal same-level move seems oddly asymmetric. Introduces Shogi generals is a great idea but you do need to use the true inter-level diagonal - which on closer examination I notice is the vertical move up or down two levels!

Mark Thompson wrote on 2003-06-21 UTC
I've been thinking lately that the 84-cell tetrahedral board might adapt better to a 3D Shogi. My reasoning is that Shogi pieces are less powerful than Chess pieces, getting much of their value from being parachutable once captured, and the difficulty of visualizing moves on this board might be lessened for less powerful pieces. I'm considering replacing the Rooks with Lances that can only move orthogonally 'forward', the Dabbabantes with some kind of Silvers and Golds that can only move to a subset of the adjacent cells, and having a Horse (a Knight, but only with its forwardmost moves) that automatically drops into the King's starting square whenever the King first vacates it. I don't think I'd include any pieces like the Shogi Bishop or Rook. The board's colors could be reduced to two. Pawns might move to the forward cells of the same color, or of opposite color, or there might be two kinds of Pawn. A Silver and Gold would move to any of the four forward cells, or to the adjacent lateral or rear cells that are the opposite color (Silver) or the same color (Gold, considering the same-levels cells 'diagonally' adjacent as adjacent for this purpose). It appeals to me that the board is also nearly the same size as a conventional Shogi board. These armies would be a bit smaller, but I think they're also a bit stronger.

Charles Gilman wrote on 2003-06-21 UTCGood ★★★★
There is a sensible diagonal move on your board, although I can see why you did you not use it as it is complex. On one level (literally rather than the usual metaphorically!) the diagonal move is self-evident, along path constant in colour and also in either letter or number. What a diagonal move between levels means is determined by observing that the board can be rotated into five other positions in the same frame (and reflected into another six), which your noation recognises as they split evenly into your levels I-VII, red-blue and green-yellow levels 1-7, and red-yellow and blue-green levels a-g, revealing such diagonals as all the c4 squares. Temperature goes out of the window (metaphorically rather than the usual literally!), but is hardly needed once a diagonal capture has been found for the Pawn. As well as this lot the board can be viewed with any corner as a hexagonal cell at the top and the rest of it as six progressively larger triangles of such cells down to 28 at the bottom. Each hex level has all four colours and the diagonal move described in my first paragraph requires a change of hex level.

Mark Thompson wrote on 2002-12-01 UTC
As of November 30, 2002, there is a new and corrected version of the ZRF available for download. If you downloaded the ZRF before that date, the version you have has a bug (sorry!), which causes it to allow the Dababante to move past an enemy piece on a square that it could have captured. As described above, every line of squares on this board alternates between two colors, and the normal move for the Dababante is to those squares that share the color of its starting square; and it can reach those squares even if a piece (other than a Pawn) intervenes on one of the squares of the other color. BUT, it CANNOT continue past a piece occupying a square of the same color as its starting square -- a piece on a square where its own motion would 'touch down' (possibly to capture the piece). This is what the earlier, incorrect version of the ZRF allowed. My thanks to Dan Troyka for figuring out how to fix this error in the ZRF. By the way, the new version also has a modified board image, making it look more like the 3-D levels are separated by struts instead of attached to upright wooden planks. Dan and I both prefer the new image.

Mark Thompson wrote on 2002-10-06 UTC
Have you actually built a board? I haven't done that yet myself, so yours would probably be the first one in existence. I'm inclining toward plexiglas levels, held up by threaded metal rods (with nuts to hold the boards in place), and a wooden base, probably made from a round cutting-board. I might want to make a set of squat chessmen somehow too, since standard chessmen seem too tall for a convenient 3-D game. They force the levels too far apart.

LCC wrote on 2002-09-28 UTCExcellent ★★★★★
This has perhaps the most interesting geometry in a chess variant ever. And if you take the time to actually make a board of the thing (paper, tape and barbecue sticks spring to mind), the gameplay isn't even as hard as in a geometrically coherent cubic chess.

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