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#Post#: 470--------------------------------------------------
Re: IMPORTANT! The 100 Post Chess Variant Contest!
By: HGMuller Date: February 15, 2018, 5:16 pm
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Now the official submission term closes, it is perhaps a good
time to also post a public description of the variant 'Decimaka'
that I submitted.
Introduction
Decimaka is an attempt to translate the unique game dynamics of
the historic Japanese Chess variant Maka Dai Dai Shogi to a
context of wetern Chess, with a manageable size. Maka Dai Dai
Shogi itself is played on a 19x19 board with 96 pieces per
player, which makes it unplayable except for the most tenacious.
Which really is a pity, as it is unlike any other Chess variant.
The set of participating pieces in Decimaka was made suitable
for this by supplementing the orthodox Chess pieces with a
number of uncommon, but otherwise ot very special pieces.
At first glance there isn't much novelty in Decimaka: is uses a
10x10 board (of course, as that was a requirement for the
contest), about half filled with pieces. The orthodox pieces
King, Rook, Bishop, Knight and Pawn appear in the initial setup,
and the fairy pieces that are added are all 'regular Chess
pieces', i.e. they all capture as they move, by replacement, and
have no side effectts on other pieces. Their moves are direct
leaps or slides along orthogoal or diagonal paths.
Promotion rules
What distinguishes Decimaka from virtually all other variants
are its promotion rules. For one, it is not just Pawns that can
promote, but most other pieces do so as well. But there is no
promotion choice; for each promoting piece it is predetermined
what it will promote to. People familiar with Shogi (Japanese
Chess) will recogize this as typical for Shogi variants. The
Pawns in Decimaka are just regular FIDE Pawns, however (apart
from their promotion), so Decimaka is not really a Shogi
variant.
What is really unusual is that the right to promote is not
derived from reaching some promotion rank at the opposite end of
the board, but can be granted anywhere on the board: whenever a
promotable piece makes a capture it can promote. In some
situations this is even mandatory, on other occasions the player
making the capture has the choice to promote the piece to its
predetermined promoted form, or leave it as it is. This is
important, because the promoted form is sometimes inferior to
the original piece, so that promotion can be a curse rather than
a blessing. The rule is that the promoted state is 'contageous':
when you capture a promoted piece the latter is gone, the
capturer catches the 'disease'. So when you capture a promoted
piece you must promote, but when you capture an unpromoted
piece, you have the choice whether to promote or not.
Pieces in Decimaka come in four kinds:
[list type=decimal]
[li]Non-promoting: King, Rook and Bishop. Other pieces capturing
those don't have to promote.[/li]
[li]Weak promotion: Pawns. These promote to omni-directional
Pawns ('Omni' for short), which move one step orthogonally and
capture one step diagonally in every direction. They are not
that much stronger than a Pawn, but because they are promoted
they are sortt of immune to attacks by pieces that you'd rather
not promote, which can make them a real pain in the ...[/li]
[li]Strong promotions: Knight, Tee and Fiancee. These are
leapers or even steppers, but promotion turns them into riders /
sliders with the same moves. So a Knight becomes a Nightrider, a
Fiancee (a non-royal King) turns into a Queen, and a Tee (so
called because its 3 forward steps and step straight backwards
define a T pattern) turns into a Trident, moving like a Rook
along files, and like a Bishop on forward diagonals.[/li]
[li]Demotions: Lion, Star, Cross and Y turn into a comparatively
worthless Omni. Expecially for the Lion and the Star this is
pretty disastrous, and thus suppresses their value when the
number of promoted opponent pieces goes up during the game.[/li]
[/list]
Pieces
The Pawn, Knight, Bishop, Rook, Queen and King move as in
orthodox Chess; the King moves 3 squares on castling. The Lion
and Star are pieces with 24 direct (i.e. unblockable) leaps,
which would make them worth more than a Queen on an 8x8 board
(11 vs 9), if it were not for the fact that they cannot capture
promoted pieces without 'selfdestructing', i.e. demote to a very
weak minor. The other unorthodox pieces are of 'Knight class' or
weaker: they are leapers with 9, 8 or even only 4 targets. The
latter one makes up for its low mobility by promoting to a
Rook-class piece. The move diagrams are as follows:
[code]. . . . . . . . . .
. . . . . . . . . .
. . . * * * * * . .
. . . * * * * * . .
. . . * * L * * . . Lion (* = direct leap)
. . . * * * * * . .
. . . * * * * * . .
. . . . . . . . . .
. . . . . . . . . .
. . . . . . . . . .
. . . . . . . . . .
. * . . * . . * . .
. . * . * . * . . .
. . . * * * . . . .
. * * * S * * * . . Star
. . . * * * . . . .
. . * . * . * . . .
. * . . * . . * . .
. . . . . . . . . .
. . . . . . . . . .
. . . . . . . . . .
. * . . . . . * . .
. . * . . . * . . .
. . . * . * . . . .
. . . . Y . . . . . Y
. . . . * . . . . .
. . . . * . . . . .
. . . . * . . . . .
. . . . . . . . . .
. . . . . . . . . .
. . . . . . . . . .
. . . . . . . . . .
. . . . . . . . . .
. . . * * * . . . .
. . . . T . . . . . Tee
. . . . * . . . . .
. . . . . . . . . .
. . . . . . . . . .
. . . . . . . . . .
. . . . . . . . . .
o . . . o . . . o .
. o . . o . . o . .
. . o . o . o . . .
. . . o o o . . . .
. . . .+T . . . . . Trident (promoted Tee), o = sliding move
. . . . o . . . . .
. . . . o . . . . .
. . . . o . . . . .
. . . . o . . . . .
. . . . o . . . . .
. . . . . . . . . .
. . . . . . . . . .
. . . . . . . . . .
. . . c m c . . . .
. . . m O m . . . . Omni (m = non-capture, c = capture)
. . . c m c . . . .
. . . . . . . . . .
. . . . . . . . . .
. . . . . . . . . .
. . . . . . . . . .
. . . . . . . . . .
. . . . . . . . . .
. . . . * . . . . .
. . . . * . . . . .
. . * * C * * . . . Cross
. . . . * . . . . .
. . . . * . . . . .
. . . . . . . . . .
. . . . . . . . . .
. . . . . . . . . .
. . o . . . o . . .
. . . . . . . . . .
o . . o . o . . o .
. . o . . . o . . .
. . . .+N . . . . . Nightrider (promoted Knight)
. . o . . . o . . .
o . . o . o . . o .
. . . . . . . . . .
. . o . . . o . . .
. . . . . . . . . .
. . . . . . . . . .
. . . . . . . . . .
. . . . . . . . . .
. . . . * * * . . .
. . . . * F * . . . Fiancee
. . . . * * * . . .
. . . . . . . . . .
. . . . . . . . . .
. . . . . . . . . .
. . . . . . . . . .
[/code]
Tactics
It is common Chess lore that complex tactical exchanges are best
started with the least valuable piece. Promotion upsets this,
however, as is already apparent in orthodox Chess: when multiple
pieces attack the same opponent on the promotion rank, you gain
most by saving the Pawn capture for last, to be left with a
Queen rather than something else.
The same considerations are important in Decimaka, to a much
larger extent, as virtually all tactics can involve promotions.
The 'winner' of a tactical exchange (in the sense that he makes
the last capture to the square) will always have the option to
promote the last capturer, and therefore should in general save
the piece that is most valuable after promotion for last. For
pieces that won't survive the exchange it hardly matters whether
they promote, and they should be accounted as they are before
engaging.
There is a twist, however, because some of the pieces would lose
value on promotion, and might be forced to promote. E.g. when an
unprotected Omni, worth only half a Knight or so, would be
captured by a Star, the latter would suffer a forced demotion,
because the Omni is a promoted piece. So the net balance of the
trade would be a Queen-class Star for two Omnis, plus loss of a
tempo (as the opponent does not even have to recapture). It is
like the Omni 'self-protects' against the valuable demoting
pieces Lion and Star.
In longer capture sequences, the side that is going to lose the
exchage (i.e. would not make the last capture) can try to use
such self-protection for the last capture he can make. E.g. if a
Cross is attacked by a Y and protected by a Star, you can
capture it and promote the Y (to Omni). This gained you an Omni
+ Cross at the expense of a Y, but the Omni self-protects
against the Star. If you had not promoted the Y, the Star could
have safely recaptured it, and you would have traded Y for
Cross, coming out an Omni less.
Non-promoting pieces (Bishop and Rook) play an important rule in
this, as they are able to break the contageon of promotion,
capturing a promoted piece, and still leaving an unpromoted one
in its place. This means the cannot be used to force the final
capturer to promote. Which again means you probably would not
want to safe them for your last capture, if the opponent would
only have demoting pieces left to retaliate. So if you attack
someting with Rook + Tee, and it is protected by Omni + Lion, it
would be best to start capturing with the Rook, and after
recapture by the Omni promote the Tee in the second capture. As
a Trident is similar to a Rook (perhaps a little bit stronger,
because more of its moves are directed forward) you only lost
the Tee at that point, for the Omni and the origial occupant,
and the Trident still effectively self-protects against the Lion
(as Lion > Trident + Omni). Had you started with the (less
valuable) Tee, you could not have followed up with the Rook, as
a Rook does not self-protect. When the opponent's second
protector would have been a non-demoting piece, nothing could
deter him from making the last capture.
These examples also show that eve initially, without ay promoted
pieces on the board, demotion is an important handicap for the
pieces suffering it. Because they cannot be used to protect
something against pieces that can promote (even to weaker ones),
as they would have been promoted by the time of the recapture.
Demoting pieces can be used to gobble up unprotected unpromoted
pieces, however.
The Queen
The Queen is the strongest piece, but it is not present in the
initial setup. There is a Fiancee, which promotes to Queen,
however. So the Queen is a promoted piece, which gives it some
permanence, as promoted pieces do not promote a second time. Of
the 'super-pieces' Queen, Lion and Star it is the only one that
cannot suffer demotion.
But there is a twist to the Queen in Decimake: it is contageous.
This means that every piece that captures a Queen, turns into a
Queen. Even if it is a piece that normally cannot promote, or is
already promoted. Only a King is exempt from this rule
('immune'). This means it is not easily possible to trade
Queens, as the side making the last capture to a square where a
Queen dwells will always end there as a Queen. Except when it
was the King, but the King usually does not get involved in
tactics before the end-game.
Strategy
The Lion and the Star are highly mobile pieces, which tend to
seek each other out to neutralize each oher's attacks. Then they
get easily traded, as there is no provision to preserve these
pieces, as there exists for Queens. Trading can be discouraged,
however, by keeping them protected by a piece with a strong
promotion, such as the Tee or Fiancee.
That there is no promotion without capture means that you ca get
stuck with unpromoted pieces in the end-game. This is quite
different in games with a promotion zone, where it becomes
progressively more easy to reach the zone as the board
population thins. So if you are left with King + Tee vs King, it
has become impossible to promote the Tee to Trident, and the
game will end in a draw, as a Tee has no mating potential.
Weak pieces, such as Pawns, therefore become a liability in the
end-game, as they can be used by the opponent to promote his
pieces. There is a strong temptation to pick off weaker opponent
pieces with your super-pieces (Queen, Lion and Star) when you
have achieved an advantage in the latter. It is much more
difficult to do this with your steppers (Fiancee, Tee, Knight),
as they typically ae far away, and move slowly. But the strong
pieces do not improve on promotion, and by annihilating all
undefensible targets with them, you will deny your steppers to
cash in on their strong promotions. It is therefore important to
develop your steppers, so they can participate in the cleanup
and promote in the process.
The Fiancee and the Cross have mating potential against a bare
King, and thus are not truly minor pieces, even though they have
about the same value as Knight or Bishop. The only pieces
without mating potential are the Pawn, Omni, Tee, Knight,
Nightrider, Bishop and Y. A Pawn is virtually useless against a
bare King, as there is no opportuity to promote, and it will be
confined to its file, so we won't consider it any further. A
Lion can even force checkmate without King help. The Y is on the
brink: on an 8x8 board it does have mating potential, and any
assistance would push it over the threshold. For pairs of pieces
mate cannot be forced with 2 Omnis, 2 Tees, 2 Knights. The
combination Tee + Omni is a boundary case: building an EGT shows
this is lost in ~50% of the cases when the bare King has the
move, while for generally won end-games this is typically 25%.
(The remaining 25% being positions where one of the pieces can
be captured immediately.) Geeral draws usually have just a few
percent of lost positions. It could be that KOTK is always won
if the O or T cannot be chased to their doom. Against optimal
defense it the mate ca take 120 moves, though.
#Post#: 472--------------------------------------------------
Re: IMPORTANT! The 100 Post Chess Variant Contest!
By: ebinola Date: February 15, 2018, 7:53 pm
---------------------------------------------------------
Now that the deadline has been passed, I have to ask: who are
the judges, and who will be on the panel of playtesters?
#Post#: 475--------------------------------------------------
Re: IMPORTANT! The 100 Post Chess Variant Contest!
By: ebinola Date: February 16, 2018, 8:59 am
---------------------------------------------------------
I think I will do the same as H.G. has done and give a wee
introduction as well.
[size=12pt]SAMURAI SHOGI[/size]
Samurai shogi started as a tongue-in-cheek comment in response
to Zied Haddad's musketeer chess:
Could you imagine if someone went as far as to make such a thing
as samurai shogi? I think the Japanese would go absolutely
mental.
And, well, here it is. Samurai shogi takes inspiration from two
variants: musketeer chess, and okisaki shogi, which introduces
the chess queen and knight to the shogi board. I'm not a huge
fan of okisaki, because I think that the queen and knights upset
the balance of material strength, and while the golds and
silvers still hold some significance, they just aren't as
important as they are in shogi. But, I liked the idea of
introducing pieces that were between/greater than the values of
the bishop and rook, so I decided to tone it down a little bit.
HTML https://i.imgur.com/626So0Z.png
The setup of samurai shogi is just like the setup of regular
shogi but on a 10x10 board (the black side is promoted just for
the sake of showing their sprites). This size increase affects
the speed of the generals, and the race to mate in the endgame.
You can see that the square adjacent to each king is empty;
before a game of samurai shogi begins, Sente chooses one piece
from a pool of six to add to the game:
[list type=decimal]
[li]The Platinum General (白金将/白/PG):
Moves as a king, but is not subject to check or mate. Promotes
to the Promoted Platinum
(成白/首[sup]1[/sup]/+PG), which moves as a
platinum, a knight, or jumps 2 squares diagonally forwards[/li]
[li]The Jumping Horse[sup]2[/sup] (跳馬/跳/H):
Moves as a chess knight. Promotes to Horse General
(駒将/駒/+H), which moves as a Horse or 1
square orthogonally.[/li]
[li]The Drunk Elephant (醉象/醉/E): Moves as a
king, but cannot go directly backwards. Promotes to the Prince
(太子/太/+E), which moves as a king. The
Prince counts as a second king, and must be captured to win, if
present.[/li]
[li]The Gold Chariot (金車/[sup]3[/sup]/GC): Moves
an unlimited number of squares as a gold general. Does not
promote.[/li]
[li]The Silver Chariot (銀車/[sup]3[/sup]/SC): Moves
an unlimited number of squares as a silver general. Does not
promote.[/li]
[li]The Samurai (武士/武/SA): Moves 1 square
orthogonally or jumps 2 squares diagonally. This is the move of
the phoenix in larger shogi variants. Promotes to Daimyo
(大名/大/+SA), which moves as a samurai or
jumps 2 squares orthogonally. This is the move of the champion
from omega chess.
[/list]
Here are the moves, in spoilers (unpromoted on left, promoted on
right):
[spoiler=Platinum General]
HTML https://i.imgur.com/xrL3To9.png<br
/>
HTML https://i.imgur.com/ZUJTGDi.png[/spoiler]
[spoiler=Jumping Horse]
HTML https://i.imgur.com/0eqEruG.png<br
/>
HTML https://i.imgur.com/n7dSzal.png[/spoiler]
[spoiler=Drunk Elephant]
HTML https://i.imgur.com/c58Hsds.png<br
/>
HTML https://i.imgur.com/PHiuUPc.png[/spoiler]
[spoiler=Gold Chariot]
HTML https://i.imgur.com/8ydEDDK.png[/spoiler]
[spoiler=Silver
Chariot]
HTML https://i.imgur.com/K9koNoQ.png[/spoiler]
[spoiler=Samurai]
HTML https://i.imgur.com/Golt1Wy.png<br
/>
HTML https://i.imgur.com/WUNcoPo.png[/spoiler]
HOWEVER. Gote has the power to refute sente's choice. When sente
chooses the piece, gote can respond with either はい
(hai/yes, I agree), or ノー (no/no, I disagree). If
gote refuses sente's choice, the samurai will be used as a
default. If the samurai is the piece being refuted, the platinum
general. Players then place the selected pieces next to their
kings, remove the other extra pieces from play, and the game
begins.
[size=12pt]DROPS[/size]
It seems unusual that in larger shogi variants, the iconic drop
rule is all but absent. Experiments with these variants have
shown that incorporating drops make many of the weaker pieces
innocent bystanders as the more powerful pieces are constantly
dropped back onto the board.
Samurai shogi, however, features shogi's drop rule, and for sake
of clarification I will explain drops here.
With the exception of the prince, captured pieces are not
removed from play. Instead, they go into your hand. If you have
pieces in your hand, instead of making a move, you can drop a
piece from your hand back onto any unoccupied square of the
board as your own! There are a few exceptions to this, however:
[list]
[li] You cannot drop a pawn to give checkmate.[/li]
[li] You cannot drop a piece where it would be stuck for the
rest of the game, i.e. you can't drop a pawn/lance on your last
rank, or a knight on your second of last rank, because they
can't go anywhere.[/li]
[li] You cannot drop a pawn on a file that already contains one
of your pawns.[/li]
[li] (for sake of reiteration) Princes cannot be dropped, they
are removed from play entirely. Drunken elephants, however, can
be captured and dropped as normal.[/li]
[/list]
Drops drastically increase the complexity of shogi (and any
variant, for that matter). Don't be fooled, though - samurai
shogi, with its extra major piece and bigger board, is
drastically different from vanilla shogi.
A 9x9 variant is possible with the extra piece being placed
anywhere on the second rank of your camp, but all the same, the
extra piece means that not only does a lot of Ranging Rook
theory need rewriting, but Static Rook suffers as well. Anyone
who has an intimate knowledge of shogi will be able to identify
all the things that you break with the addition of these things.
But hey, that's chess variants for you.
Other rules are exactly identical to that of shogi: see
HTML https://en.wikipedia.org/wiki/Shogi
for more info.
1 - I'm cheating a little bit here. This character means chief,
one who leads, etc. but it bears resemblence to 白, so it
shall be used in its place.
2 - Originally 'white horse,' but to avoid confusion with the
white horse in chu shogi, and the fact that another piece has
白 in its name, I changed it to the name used for the
knight used in okisaki shogi. This allows for 2 unique
characters that can be used to notate this piece in traditional
Japanese notation.
3 - Yeah, I couldn't find a character for these guys. I don't
know if in larger shogi variants people have to write both
characters to notate which piece is being moved (due to the
large variety of pieces), but I hope this isn't too jarring for
people who use traditional notation.
#Post#: 478--------------------------------------------------
Re: IMPORTANT! The 100 Post Chess Variant Contest!
By: HGMuller Date: February 16, 2018, 11:39 am
---------------------------------------------------------
The commonly given explanation as to why the Elephant was ousted
from Sho Shogi when drops were introduced is that it would
enormously drive up the occurrence of 'impasse': in stead of
walking the King to the opponent camp, with very low survival
probablilty on the way, you just drop the Elephant there, and
promote it. You can do that any time when you got a foothold in
the opponent camp.
Not allowing a Prince to return doesn't solve this. You could
still drop the Elephant in the zone (one would expect the Prince
to revert to Elephant anyway, on capture), to get a Prince there
one move later. And you can do that after you built a fortress
there from some Tokins. I guess you should also forbid dropping
the Elephant. But as you already have several alternative
choices for the Elephant, I don't think it would be a great loss
if you abandoned it altogether. Then you would not need special
rules for it.
#Post#: 479--------------------------------------------------
Re: IMPORTANT! The 100 Post Chess Variant Contest!
By: ebinola Date: February 16, 2018, 11:58 am
---------------------------------------------------------
There's also handicaps to think about. The elephant, on its own,
is the weakest of the pieces. Stronger than a gold but not as
strong as the others.
I just read Asher's comment, the deadline has been extended,
so... would it even be fair for me to revise the rules?
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