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Chak. A modern vision of what a Mayan chess would look like.[All Comments] [Add Comment or Rating]
H. G. Muller wrote on 2022-01-20 UTC

Nice! One thing I notice is that the script asks if you want to promote -- it's mandatory and not a choice.

Good point. I used the regular Shogi-style promotion supported by the Diagram, which always offers the choice. It is possible to implement mandatory promotion by supplying an additional JavaScript routine WeirdPromotion() on the page, which is a bit of a hassle. Perhaps I should support an alternative method for declaring promotion mandatory, e.g. through the already existing promoChoice parameter to the Diagram. With Shogi-style promotions this is currently not used. It would be logical to let the setting + mean mandatory promotion, and += that there is a choice. Unfortunately this is not backward compatible with Diagrams of games with Shogi-style promotion I (and others) made in the past, which often specify promoChoice as just +,  or not at all. I will give it some thought how best to make this a standard feature of the Diagram.

[Edit] OK. I fixed it by using a newly added feature of the Diagram (so only active after refresh of the browser cache): if the promoChoice string contains !L in some variant with Shogi-style promotion (i.e. promoOffset non-zero), the piece with ID L will not be allowed to defer, and will promote automatically on reaching the zone. This was inspired on the same notation being used with Chess-style promotions for indicated that the choice is not allowed on last rank. (Which is commonly used to force promotion of a Pawn there when promotion on other ranks is optional.)

Daniel Lee wrote on 2022-01-19 UTC

Nice! One thing I notice is that the script asks if you want to promote -- it's mandatory and not a choice.

H. G. Muller wrote on 2022-01-16 UTC

Interesting variant. The following Diagram gives a good approximation. (Requires a refresh of the browser cache, to make pieces without any moves work.)

ranks=9 files=9 graphicsDir=../graphics.dir/alfaeriePNG35/ whitePrefix=w blackPrefix=b graphicsType=png squareSize=35 symmetry=rotate promoZone=5 promoOffset=8 promoChoice=!P!K maxPromote=2 royal=2 royal=10 stalemate=win counterbare=lose pawn::fsmWfcF::a3,c3,e3,g3,i3 king::K::e1 offering::-:ram:e2 shaman::FvW:guard:c1,g1 vulture::N:knight:b1,h1 serpent:R:R:rook:a1,i1 quetzal::pQ:paovao:f1 jaguar::KN:knightguard:d1 warrior::FvW:berolinapawn: divine king::Q2:falcon:

I also had to implement something for winning by reaching a target square. Such a game rule is also encountered in King of the Hill and Kahn Chess. For the moment this is handled through the routine BadZone() in a user-supplied script, (which was needed here anyway for preventing promoted pieces move back into their own half): when this function returns -1 the Diagram's standard script now interprets this as a winning move, rather than a forbidden move. Such a win is treated as baring in Shatranj, so that there is an after-move for proving the move was legal, and would declare a loss instead if it exposed royalty to capture. This again required the result of counter-baring to be specified by a parameter, (rather than always being a draw), as it should not be possible to draw here by reaching the Altar on the half-move following the one where the opponent did.

Daniel Lee wrote on 2022-01-16 UTC

Oops, I think I lost the image for that. I'll update.

Jean-Louis Cazaux wrote on 2022-01-15 UTC

Great looking, nice thema. What I have not understood reading the rules, is how the pieces start? What is the initial setup?

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