run tidy over html files; added include for gnu pages

[xboard.git] / whats_new / rules / ChuChess.html

<!--#include virtual="/server/html5-header.html" -->
  <title>Chu Chess</title>
  <link rel="StyleSheet" href="./moves.css" type="text/css">
  <script type="text/javascript" src="chu.js">
</script>
<!--#include virtual="/server/banner.html" -->
<!--#set var="article_name" value="/server/standards/boilerplate" -->
<!--#include virtual="/server/gnun/initial-translations-list.html" -->

  <h1>Chu Chess</h1>

  <p>Chu Chess is an intermediate between (Mighty-Lion) Chess and
  Chu Shogi. It was designed for over-the-board play with the aid
  of two Chess sets, some draughts chips, and an
  International-Daughts (10x10) board. Pieces placed on a
  draughts-chip pedestal would represent 'crowned' pieces, i.e.
  pieces that in addition to their normal Chess moves would also be
  able to move as an orthodox King. With the exception of the
  Knight on a pedestal, which would not only get the extra King
  move, but the full power of a Chu-Shogi Lion. (To highlight its
  importance, it could be put on top of a stack of draughts chips.)
  This variant can be played in two versions, differing only in
  promotion rules, which can be either Chess-like or
  Shogi-like.</p>

  <table cellpadding="20">
    <tr>
      <td><img src="ChuChess.png"></td>

      <td>
        <h3>Initial setup</h3>

        <p>f0, e9: King<br>
        e1, f8: Lion<br>
        f1, e8: Queen<br>
        g1, d8: Crowned Rook<br>
        d1, g8: Crowned Bishop<br>
        a0, a9, j0, j9: Rook<br>
        c1, c8, h1, h8: Bishop<br>
        b1, b8, i1, i8: Knight<br>
        a1, a8, j1, j8: Commoner<br>
        a2-j2, a7-j7: Pawns</p>
      </td>
    </tr>
  </table>

  <h3>Moves at a Glance</h3>

  <p>Click on a piece below to see its moves</p>

  <table class="board">
    <tr>
      <td class="n" id="sq0x9" onmousedown="down_click(0,-9)"
      onmouseup="up_click()"><img src="sym/BlackRook.png"></td>

      <td class="n" id="sq1x9"></td>

      <td class="n" id="sq2x9"></td>

      <td class="n" id="sq3x9"></td>

      <td class="n" id="sq4x9" onmousedown="down_click(4,-9)"
      onmouseup="up_click()"><img src="sym/BlackKing.png"></td>

      <td class="n" id="sq5x9"></td>

      <td class="n" id="sq6x9"></td>

      <td class="n" id="sq7x9"></td>

      <td class="n" id="sq8x9"></td>

      <td class="n" id="sq9x9" onmousedown="down_click(9,-9)"
      onmouseup="up_click()"><img src="sym/BlackRook.png"></td>

      <td class="h"><img src="sym/yellow.png"></td>

      <td class="w" rowspan="2" valign="top">
        <p>Sliding capture or non-capture,<br>
        can be blocked on any square along the ray</p>
      </td>
    </tr>

    <tr>
      <td class="n" id="sq0x8"></td>

      <td class="n" id="sq1x8"></td>

      <td class="n" id="sq2x8"></td>

      <td class="n" id="sq3x8"></td>

      <td class="n" id="sq4x8"></td>

      <td class="n" id="sq5x8"></td>

      <td class="n" id="sq6x8"></td>

      <td class="n" id="sq7x8"></td>

      <td class="n" id="sq8x8"></td>

      <td class="n" id="sq9x8"></td>
    </tr>

    <tr>
      <td class="n" id="sq0x7"></td>

      <td class="n" id="sq1x7"></td>

      <td class="n" id="sq2x7"></td>

      <td class="n" id="sq3x7"></td>

      <td class="n" id="sq4x7"></td>

      <td class="n" id="sq5x7"></td>

      <td class="n" id="sq6x7" onmousedown="down_click(6,7)"
      onmouseup="up_click()"><img src="sym/WhiteCommoner.png"></td>

      <td class="n" id="sq7x7"></td>

      <td class="n" id="sq8x7"></td>

      <td class="n" id="sq9x7"></td>

      <td class="h"><img src="sym/orange.png"></td>

      <td class="w">Unblockable leap (capture or non-capture)</td>
    </tr>

    <tr>
      <td class="n" id="sq0x6"></td>

      <td class="n" id="sq1x6"></td>

      <td class="n" id="sq2x6"></td>

      <td class="n" id="sq3x6"></td>

      <td class="n" id="sq4x6"></td>

      <td class="n" id="sq5x6"></td>

      <td class="n" id="sq6x6" onmousedown="down_click(6,6)"
      onmouseup="up_click()"><img src="sym/WhiteKing.png"></td>

      <td class="n" id="sq7x6"></td>

      <td class="n" id="sq8x6"></td>

      <td class="n" id="sq9x6"></td>

      <td class="h"><img src="sym/green.png"></td>

      <td class="w">Non-capture only</td>
    </tr>

    <tr>
      <td class="n" id="sq0x5"></td>

      <td class="n" id="sq1x5"></td>

      <td class="n" id="sq2x5"></td>

      <td class="n" id="sq3x5"></td>

      <td class="n" id="sq4x5"></td>

      <td class="n" id="sq5x5"></td>

      <td class="n" id="sq6x5" onmousedown="down_click(6,5)"
      onmouseup="up_click()"><img src=
      "sym/WhiteCrownedRook.png"></td>

      <td class="n" id="sq7x5" onmousedown="down_click(7,5)"
      onmouseup="up_click()"><img src="sym/WhiteRook.png"></td>

      <td class="n" id="sq8x5"></td>

      <td class="n" id="sq9x5"></td>

      <td class="h"><img src="sym/red.png"></td>

      <td class="w">Capture only</td>
    </tr>

    <tr>
      <td class="n" id="sq0x4"></td>

      <td class="n" id="sq1x4"></td>

      <td class="n" id="sq2x4"></td>

      <td class="n" id="sq3x4"></td>

      <td class="n" id="sq4x4" onmousedown="down_click(4,4)"
      onmouseup="up_click()"><img src="sym/WhiteLion.png"></td>

      <td class="n" id="sq5x4" onmousedown="down_click(5,4)"
      onmouseup="up_click()"><img src="sym/WhiteQueen.png"></td>

      <td class="n" id="sq6x4" onmousedown="down_click(6,4)"
      onmouseup="up_click()"><img src=
      "sym/WhiteCrownedBishop.png"></td>

      <td class="n" id="sq7x4" onmousedown="down_click(7,4)"
      onmouseup="up_click()"><img src="sym/WhiteBishop.png"></td>

      <td class="n" id="sq8x4"></td>

      <td class="n" id="sq9x4"></td>

      <td class="h"><img src="sym/cyan.png"></td>

      <td class="w" rowspan="2" valign="top">Captured while passing
      through the square to another destination</td>
    </tr>

    <tr>
      <td class="n" id="sq0x3"></td>

      <td class="n" id="sq1x3"><img src="sym/BlackPawn.png"></td>

      <td class="n" id="sq2x3"></td>

      <td class="n" id="sq3x3"></td>

      <td class="n" id="sq4x3" onmousedown="down_click(4,-3)"
      onmouseup="up_click()"><img src="sym/WhiteKnight.png"></td>

      <td class="n" id="sq5x3"></td>

      <td class="n" id="sq6x3"></td>

      <td class="n" id="sq7x3"></td>

      <td class="n" id="sq8x3"></td>

      <td class="n" id="sq9x3"></td>
    </tr>

    <tr>
      <td class="n" id="sq0x2"></td>

      <td class="n" id="sq1x2"></td>

      <td class="n" id="sq2x2"></td>

      <td class="n" id="sq3x2"></td>

      <td class="n" id="sq4x2"></td>

      <td class="n" id="sq5x2"></td>

      <td class="n" id="sq6x2"></td>

      <td class="n" id="sq7x2" onmousedown="down_click(7,2)"
      onmouseup="up_click()"><img src="sym/WhitePawn.png"></td>

      <td class="n" id="sq8x2"></td>

      <td class="n" id="sq9x2"></td>
    </tr>

    <tr>
      <td class="n" id="sq0x1"></td>

      <td class="n" id="sq1x1"></td>

      <td class="n" id="sq2x1" onmousedown="down_click(2,1)"
      onmouseup="up_click()"><img src="sym/WhitePawn.png"></td>

      <td class="n" id="sq3x1"></td>

      <td class="n" id="sq4x1"></td>

      <td class="n" id="sq5x1"></td>

      <td class="n" id="sq6x1"></td>

      <td class="n" id="sq7x1"></td>

      <td class="n" id="sq8x1"></td>

      <td class="n" id="sq9x1"></td>
    </tr>

    <tr>
      <td class="n" id="sq0x0"></td>

      <td class="n" id="sq1x0"></td>

      <td class="n" id="sq2x0"></td>

      <td class="n" id="sq3x0"></td>

      <td class="n" id="sq4x0"></td>

      <td class="n" id="sq5x0"></td>

      <td class="n" id="sq6x0"></td>

      <td class="n" id="sq7x0"></td>

      <td class="n" id="sq8x0"></td>

      <td class="n" id="sq9x0"></td>
    </tr>
  </table>

  <p id="piece" height="20">:<br>
  :<br>
  :<br>
  :</p>

  <table cellpadding="5" border="1">
    <tr>
      <td>Piece</td>

      <td>ID</td>

      <td>value</td>

      <td>Moves (<a href="Betza.html">Betza notation</a>)</td>

      <td>Remarks</td>
    </tr>

    <tr>
      <td>King</td>

      <td>K</td>

      <td>-</td>

      <td>K</td>

      <td>Can castle with Rook, moving 3 steps towards it</td>
    </tr>

    <tr>
      <td>Lion</td>

      <td>L</td>

      <td>15</td>

      <td>KNAD(cK-aK)(K-bK)</td>

      <td>Can make two independent King steps per turn (capturing
      upto two pieces)</td>
    </tr>

    <tr>
      <td>Queen</td>

      <td>Q</td>

      <td>9.5</td>

      <td>RB or Q</td>

      <td></td>
    </tr>

    <tr>
      <td>Crowned Rook</td>

      <td>+R</td>

      <td>7</td>

      <td>RF</td>

      <td>aka Dragon Kin</td>
    </tr>

    <tr>
      <td>Crowned Bishop</td>

      <td>+B</td>

      <td>5.25</td>

      <td>BW</td>

      <td>aka Dragon Horse</td>
    </tr>

    <tr>
      <td>Rook</td>

      <td>R</td>

      <td>5</td>

      <td>R</td>

      <td></td>
    </tr>

    <tr>
      <td>Bishop</td>

      <td>B</td>

      <td>3.5</td>

      <td>B</td>

      <td>Color-bound</td>
    </tr>

    <tr>
      <td>Knight</td>

      <td>N</td>

      <td>3</td>

      <td>N</td>

      <td></td>
    </tr>

    <tr>
      <td>Commoner</td>

      <td>M</td>

      <td>3</td>

      <td>K</td>

      <td>aka Man or Soldier</td>
    </tr>

    <tr>
      <td>Pawn</td>

      <td>P</td>

      <td>1</td>

      <td>mfWcfF</td>

      <td>Promotes to Q, R, B, or N on reaching promotion zone</td>
    </tr>
  </table>

  <h3>Pawn peculiarities</h3>

  <ul>
    <li>Pawns capture differently from how they move (straight
    move, diagonal capture).</li>

    <li>Pawns can move two squares straight ahead from their
    initial position, provided they are not blocked.</li>

    <li>On the move immediately after such a double push, they can
    be captured en passant by another Pawn, as if they had only
    moved 1 square ahead.</li>

    <li>Pawns promote asthey promote in orthodox Chess piece of
    choice when they enter the promotion zone (in the Chess-like
    version).</li>
  </ul>

  <h3>Castling</h3>

  <p>A King that has not moved before can move <b>three</b> squares
  in the direction of a Rook that has not moved before, in which
  case that Rook is moved to the square the King skipped over. This
  is only allowed if all squares between King and Rook are empty,
  when the King is not in check on the square it came from, and
  would not be in check on any of the squares it skipped over.</p>

  <h3>General rules</h3>

  <ul>
    <li>It is not allowed to expose your King to check.</li>

    <li>The game is won by checkmating the opponent's King.</li>

    <li>Stalemate (no legal moves, but not in check) is a
    draw.</li>

    <li>The promotion zone is three ranks deep.</li>

    <li>You cannot promote to Lion if you already have one.</li>
  </ul>

  <h3>Chess-like or Shogi-like promotion</h3>

  <p>In the Chess-like version only Pawns promote. You can choose
  what piece to promote to, but promotion is mandatory: you cannot
  stay a Pawn. In the Shogi-like version other pieces can also
  promote, but there is no choice: pieces promote to their
  'crowned' versions, and acquire the moves of a King on top of
  their own that way. Pieces that already had all King moves cannot
  promote. Thus a Commoner cannot Promote, and a Pawn can only
  promote to Commoner. The Knight promotes to Lion, and thus gains
  unusually much in value.</p>

  <h3>The Lion piece</h3>

  <p>The Lion can make two moves per turn. That means it can also
  capture two pieces per turn, one on the square it moves to (as
  normal), and one 'en passant' on the transit square. It can also
  capture on the transit square, and move on to an empty square
  ('hit and run'), or capture and move back to where it came from
  ('shooting' the piece from a distance, as it were). Of course it
  can also capture a single piece in the normal Chess manner. In
  that case the transit square is immaterial.</p>

  <p>The Lion can make such double moves as two King steps, i.e. in
  all directions, and arbitrarily changing direction between them.
  It can also jump over the transit square, i.e. reach the distant
  two-step destination in a single jump. Finally it can also just
  make a step to an adjacent square, refraining from taking a
  second step.</p>

  <h3>Restrictions on Lion capture</h3>

  <p>There are rules to make Lion trading very difficult, in order
  to keep the Lions in play. Basically they specify that two Lions
  cannot be captured in consecutive half-moves. When the first
  capture is Lion x Lion from a distance, it is forbidden to play
  it if pseudo-legal (i.e. without taking account of check)
  recapture of the capturing Lion is possible <i>with another piece
  than King</i>. So even when the Lion is protected only with a
  pinned piece, the other Lion cannot capture it <i>from a
  distance</i>, just like a King could not capture it.</p>

  <p>When a non-Lion captures a Lion, it is just the other way
  around: then the 'counterstrike' by a non-Lion against the Lion
  is forbidden. One possibility left open is thus when you capture
  an adjacent Lion. But then you would in general be foolish to
  allow recapture, as you could take the Lion hit-and-run fashion,
  fleeing to a save square. An exception to the rule is when a
  valuable opponent piece (i.e. not a Pawn) forms a 'bridge'
  between the Lions; you may then capture that piece in the first
  leg of the double-move, and then take the opponent Lion with the
  second leg. Then the opponent can recapture, but he will have
  lost a valuable piece. In the late end-game, when you have
  nothing to protect your Lion with other than King, trading
  becomes possible.</p>

  <h3>XBoard interface issues</h3>

  <p>This game has to be played with the option Show Target Squares
  on! This option will cause marking of the target squares of any
  piece you select or grab, by the engine (with legality testing
  off) or by XBoard (legality testing on). Moving to a square
  marked in cyan will be interpreted not as the final destination,
  but as the transit square after the first step of a multi-leg
  move. XBoard will then highlight the possible destination squares
  of the second leg from there. Should you want to end on the cyan
  square, you click it again, (it will be no longer marked in
  cyan), and XBoard will terminate the move after the first leg.
  You can also move back to the starting square, to 'shoot' the
  opponent piece from nearby.</p>

  <p>XBoard will allow both the Chess-like and the Shogi-like
  promotion; the engine will have to decide which promotion style
  it thinks legal. The default choice in 'sweep-promotions' mode
  will be deferral for pieces, however, to facilitate Chess-like
  play. To play a Shogi promotion in this mode you should enter it
  as a click-click move, but during the click on the promotion
  square move the mouse pointer down until the promoted piece
  appears, and only then release the mouse button. The Pawn will
  show Queen as default, and a 'dragging click' on the promotion
  square will cycle through all choices. In the Shogi version you
  would have to choose the Commoner that way. With a promotion
  popup you would have to press 'No' on piece moves into the zone
  when you play the Chess-like version, and press 'Commoner' on
  Pawn promotions when you play the Shogi-like version.</p>

  <h3>Differences with FIDE</h3>

  <p>The board is 10x10, with a 3-rank-deep promotion zone. The
  initial setup leaves an almost empty rank behind the pieces,
  where you can immediately castle. You have a Lion, Crowned Rook,
  Crowned Bishop and two Soldiers as extra pieces. In the
  Shogi-like version of the rules, some pieces other than Pawn can
  also promote.</p>

  <h3>Strategy issues</h3>

  <p>It is not possible to force checkmate on a bare King with just
  a single Bishop or Knight (in addition to your own King). Two
  Knights cannot do that either.</p>

  <p>With a single Commoner you can force checkmate on a bare
  King.</p>

  <p>Bishops are confined to squares of a single color. Having
  Bishops on both colors compensates this weakness, and is worth an
  extra 0.5 on top of their added value.</p>

  <p>A Queen is upward compatible with all weaker pieces except
  Knight. So only promotion to Queen or Knight makes sense, (except
  perhaps for rare situations where you might have to avoid
  stalemate).</p>
</div><!-- for id="content", starts in the include above -->
<!--#include virtual="/server/footer.html" -->
</body>
</html>