From 1080bc93379cd270e09f7d125e2cb95bda51f95f Mon Sep 17 00:00:00 2001
From: Benjamin Auder <benjamin.auder@somewhere>
Date: Fri, 25 Nov 2022 17:57:25 +0100
Subject: [PATCH] Work on Checkered variant

---
 variants/Checkered/complete_rules.html | 152 ++++++++++++++++++++
 variants/Checkered/pieces/cb.svg       | 173 ++++++++++++++++++++++
 variants/Checkered/pieces/cn.svg       | 101 +++++++++++++
 variants/Checkered/pieces/cp.svg       |  86 +++++++++++
 variants/Checkered/pieces/cq.svg       | 189 +++++++++++++++++++++++++
 variants/Checkered/pieces/cr.svg       | 143 +++++++++++++++++++
 variants/Checkered/rules.html          |  10 ++
 variants/Checkered/style.css           |  17 +++
 8 files changed, 871 insertions(+)
 create mode 100644 variants/Checkered/complete_rules.html
 create mode 100644 variants/Checkered/pieces/cb.svg
 create mode 100644 variants/Checkered/pieces/cn.svg
 create mode 100644 variants/Checkered/pieces/cp.svg
 create mode 100644 variants/Checkered/pieces/cq.svg
 create mode 100644 variants/Checkered/pieces/cr.svg
 create mode 100644 variants/Checkered/rules.html
 create mode 100644 variants/Checkered/style.css

diff --git a/variants/Checkered/complete_rules.html b/variants/Checkered/complete_rules.html
new file mode 100644
index 0000000..5f21663
--- /dev/null
+++ b/variants/Checkered/complete_rules.html
@@ -0,0 +1,152 @@
+<!doctype html>
+<html>
+<head>
+  <title>Checkered Rules</title>
+  <link href="/common.css" rel="stylesheet"/>
+  <link href="/variants/Checkered/style.css" rel="stylesheet"/>
+</head>
+<body>
+
+<div class="full-rules">
+<h1>Checkered Rules</h1>
+
+<div>
+<p class="boxed">
+  The capture of an enemy piece produces a new "checkered" piece belonging
+  to both players.
+</p>
+<figure class="showPieces text-center">
+  <img src="pieces/cp.svg"/>
+  <img src="pieces/cr.svg"/>
+  <img src="pieces/cn.svg"/>
+  <img src="pieces/cb.svg"/>
+  <img src="pieces/cq.svg"/>
+  <figcaption>Checkered pieces, born after captures.</figcaption>
+</figure>
+<p>Note: the initial French name for this variant is "l'Échiqueté".</p>
+<p>The game potentially evolves in two stages.</p>
+</div>
+
+<div>
+<h2 class="stageDelimiter">Stage 1</h2>
+<h3>Basics</h3>
+<ol>
+  <li>
+    Each capture produces a new piece, taking on nature of
+    the capturing or captured one.
+  </li>
+  <li>
+    The new piece arising from a capture has a new color:
+    "checkered", as illustrated above.
+  </li>
+  <li>
+    All checkered pieces belong to the player in turn and can
+    capture the opponents pieces.
+  </li>
+</ol>
+<p>Remarks:</p>
+<ul>
+  <li>
+    A non-capturing checkered move cannot be "undone" right after since
+    this would repeat the same position.
+  </li>
+  <li>Checkered pieces cannot be captured.</li>
+</ul>
+<figure class="diagram-container">
+  <div class="diagram">fen:2kr4/pp6/2p5/4ss1r/1P2ns1P/2Np4/P1P1P1BP/R2o1RK1:</div>
+  <figcaption>
+    Black plays Rxh4=P. (Checkered pawn to) h5 is allowed then,
+    because piece's nature changed.
+    
+  </figcaption>
+</figure>
+<h3>Pawns</h3>
+<ul>
+  <li>
+    Pawns can jump two squares only from their initial rank, and only once in
+    the game. A checkered pawn keeps this right if the starting pawn
+    did not use it.
+  </li>
+  <li>
+    Checkered pawns cannot capture en passant, because while the pawn was
+    "passing" they were of the same color.
+    
+  </li>
+</ul>
+<h3>Stalemate or checkmate?</h3>
+<p>
+  The following diagram seems to show a mating pattern, but the king if
+  "attacked" by a checkered pawn &ndash; which still belongs to white.
+  Therefore, it can be considered that it's not really a check because
+  white is unable to "give back the turn".
+  Without the black bishop on a7 it would be mate (without debate), because
+  the king could virtually go to g1 before being captured by the
+  chameleon pawn.
+  
+</p>
+<figure>
+  <div class="diag"
+       data-fen='7k/b5pp/8/8/8/8/6ss/7K w 4 {"flags":"88880000000000000011"}'>
+  </div>
+  <figcaption>After 1...g2+(#?).</figcaption>
+</figure>
+<p>
+  The interface considers that it's mate in both cases, following the idea
+  "it's checkmate if we cannot move, and the opponent on its turn could
+  take the king" (maybe after an impossible move).
+  
+</p>
+</div>
+
+<div>
+<h2 class="stageDelimiter">Stage 2</h2>
+<p class="italic">
+  This stage can be disabled by unselecting "With switch" at game creation.
+</p>
+<p>
+  During the game one of the two players can decide to take control of the
+  checkered pieces.
+  They thus become autonomous and vulnerable to being captured - stage 2
+  begins. The other player is in charge of both the white and black pieces, and
+  tries to eliminate checkered pieces.
+  The checkered side wins by checkmating either the white or black king.
+</p>
+<p>
+  To take the checkered pieces, play a move that "takes opponent's king" with
+  your king, and then execute a move. This is possible only if no such move
+  can capture a king.
+</p>
+<h4>Variant of stage 2 (unimplemented)</h4>
+<p>
+  An observer could decide to join the game by taking the checkered pieces
+  at any moment.
+  It then becomes a chess game with three players, with some subtelties to be
+  resolved. It was tested in some (real life) games.
+</p>
+<h3>Special moves</h3>
+<p>Checkered pawns can...</p>
+<ul>
+  <li>move and capture in either direction;</li>
+  <li>take en passant,</li>
+  <li>be promoted on either the first or eighth row.</li>
+</ul>
+</div>
+
+<div>
+<h3>Credits</h3>
+<ul>
+  <li>
+    The rules of Checkered Chess were thought up by Patrick Bernier and
+    developed with the help of Benjamin Auder around 2011-2012.
+  </li>
+  <li>
+    Thanks also to Olive Martin, Christian Poisson, Bevis Martin, Laurent
+    Nouhaud and Frédéric Fradet.
+  </li>
+</ul>
+</div>
+
+</body>
+<script src="/utils/drawDiagrams.js"></script>
+<script>fenToDiag("Checkered");</script>
+</html>
diff --git a/variants/Checkered/pieces/cb.svg b/variants/Checkered/pieces/cb.svg
new file mode 100644
index 0000000..3f32179
--- /dev/null
+++ b/variants/Checkered/pieces/cb.svg
@@ -0,0 +1,173 @@
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diff --git a/variants/Checkered/pieces/cn.svg b/variants/Checkered/pieces/cn.svg
new file mode 100644
index 0000000..5f7b3bc
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diff --git a/variants/Checkered/pieces/cr.svg b/variants/Checkered/pieces/cr.svg
new file mode 100644
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diff --git a/variants/Checkered/rules.html b/variants/Checkered/rules.html
new file mode 100644
index 0000000..892f352
--- /dev/null
+++ b/variants/Checkered/rules.html
@@ -0,0 +1,10 @@
+<p>
+  Each capture produces a new "checkered" piece which both players can use.
+  Checkered moves cannot be undone on next turn.
+</p>
+
+<a target="_blank" href="/variants/Checkered/complete_rules.html">
+  Full rules description.
+</a>
+
+<p class="author">Patrick Bernier (2012).</p>
diff --git a/variants/Checkered/style.css b/variants/Checkered/style.css
new file mode 100644
index 0000000..a6582e7
--- /dev/null
+++ b/variants/Checkered/style.css
@@ -0,0 +1,17 @@
+@import url("/base_pieces.css");
+
+piece.checkered-pawn {
+  background-image: url('/variants/Checkered/pieces/cp.svg');
+}
+piece.checkered-rook {
+  background-image: url('/variants/Checkered/pieces/cr.svg');
+}
+piece.checkered-knight {
+  background-image: url('/variants/Checkered/pieces/cn.svg');
+}
+piece.checkered-bishop {
+  background-image: url('/variants/Checkered/pieces/cb.svg');
+}
+piece.checkered-queen {
+  background-image: url('/variants/Checkered/pieces/cq.svg');
+}
-- 
2.44.0