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12 <p>Chu Chess is an intermediate between (Mighty-Lion) Chess and
13 Chu Shogi. It was designed for over-the-board play with the aid
14 of two Chess sets, some draughts chips, and an
15 International-Daughts (10x10) board. Pieces placed on a
16 draughts-chip pedestal would represent 'crowned' pieces, i.e.
17 pieces that in addition to their normal Chess moves would also be
18 able to move as an orthodox King. With the exception of the
19 Knight on a pedestal, which would not only get the extra King
20 move, but the full power of a Chu-Shogi Lion. (To highlight its
21 importance, it could be put on top of a stack of draughts chips.)
22 This variant can be played in two versions, differing only in
23 promotion rules, which can be either Chess-like or
26 <table cellpadding="20">
28 <td><img src="ChuChess.png"></td>
31 <h3>Initial setup</h3>
36 g1, d8: Crowned Rook<br>
37 d1, g8: Crowned Bishop<br>
38 a0, a9, j0, j9: Rook<br>
39 c1, c8, h1, h8: Bishop<br>
40 b1, b8, i1, i8: Knight<br>
41 a1, a8, j1, j8: Commoner<br>
42 a2-j2, a7-j7: Pawns</p>
47 <h3>Moves at a Glance</h3>
49 <p>Click on a piece below to see its moves</p>
53 <td class="n" id="sq0x9" onmousedown="down_click(0,-9)"
54 onmouseup="up_click()"><img src="sym/BlackRook.png"></td>
56 <td class="n" id="sq1x9"></td>
58 <td class="n" id="sq2x9"></td>
60 <td class="n" id="sq3x9"></td>
62 <td class="n" id="sq4x9" onmousedown="down_click(4,-9)"
63 onmouseup="up_click()"><img src="sym/BlackKing.png"></td>
65 <td class="n" id="sq5x9"></td>
67 <td class="n" id="sq6x9"></td>
69 <td class="n" id="sq7x9"></td>
71 <td class="n" id="sq8x9"></td>
73 <td class="n" id="sq9x9" onmousedown="down_click(9,-9)"
74 onmouseup="up_click()"><img src="sym/BlackRook.png"></td>
76 <td class="h"><img src="sym/yellow.png"></td>
78 <td class="w" rowspan="2" valign="top">
79 <p>Sliding capture or non-capture,<br>
80 can be blocked on any square along the ray</p>
85 <td class="n" id="sq0x8"></td>
87 <td class="n" id="sq1x8"></td>
89 <td class="n" id="sq2x8"></td>
91 <td class="n" id="sq3x8"></td>
93 <td class="n" id="sq4x8"></td>
95 <td class="n" id="sq5x8"></td>
97 <td class="n" id="sq6x8"></td>
99 <td class="n" id="sq7x8"></td>
101 <td class="n" id="sq8x8"></td>
103 <td class="n" id="sq9x8"></td>
107 <td class="n" id="sq0x7"></td>
109 <td class="n" id="sq1x7"></td>
111 <td class="n" id="sq2x7"></td>
113 <td class="n" id="sq3x7"></td>
115 <td class="n" id="sq4x7"></td>
117 <td class="n" id="sq5x7"></td>
119 <td class="n" id="sq6x7" onmousedown="down_click(6,7)"
120 onmouseup="up_click()"><img src="sym/WhiteCommoner.png"></td>
122 <td class="n" id="sq7x7"></td>
124 <td class="n" id="sq8x7"></td>
126 <td class="n" id="sq9x7"></td>
128 <td class="h"><img src="sym/orange.png"></td>
130 <td class="w">Unblockable leap (capture or non-capture)</td>
134 <td class="n" id="sq0x6"></td>
136 <td class="n" id="sq1x6"></td>
138 <td class="n" id="sq2x6"></td>
140 <td class="n" id="sq3x6"></td>
142 <td class="n" id="sq4x6"></td>
144 <td class="n" id="sq5x6"></td>
146 <td class="n" id="sq6x6" onmousedown="down_click(6,6)"
147 onmouseup="up_click()"><img src="sym/WhiteKing.png"></td>
149 <td class="n" id="sq7x6"></td>
151 <td class="n" id="sq8x6"></td>
153 <td class="n" id="sq9x6"></td>
155 <td class="h"><img src="sym/green.png"></td>
157 <td class="w">Non-capture only</td>
161 <td class="n" id="sq0x5"></td>
163 <td class="n" id="sq1x5"></td>
165 <td class="n" id="sq2x5"></td>
167 <td class="n" id="sq3x5"></td>
169 <td class="n" id="sq4x5"></td>
171 <td class="n" id="sq5x5"></td>
173 <td class="n" id="sq6x5" onmousedown="down_click(6,5)"
174 onmouseup="up_click()"><img src=
175 "sym/WhiteCrownedRook.png"></td>
177 <td class="n" id="sq7x5" onmousedown="down_click(7,5)"
178 onmouseup="up_click()"><img src="sym/WhiteRook.png"></td>
180 <td class="n" id="sq8x5"></td>
182 <td class="n" id="sq9x5"></td>
184 <td class="h"><img src="sym/red.png"></td>
186 <td class="w">Capture only</td>
190 <td class="n" id="sq0x4"></td>
192 <td class="n" id="sq1x4"></td>
194 <td class="n" id="sq2x4"></td>
196 <td class="n" id="sq3x4"></td>
198 <td class="n" id="sq4x4" onmousedown="down_click(4,4)"
199 onmouseup="up_click()"><img src="sym/WhiteLion.png"></td>
201 <td class="n" id="sq5x4" onmousedown="down_click(5,4)"
202 onmouseup="up_click()"><img src="sym/WhiteQueen.png"></td>
204 <td class="n" id="sq6x4" onmousedown="down_click(6,4)"
205 onmouseup="up_click()"><img src=
206 "sym/WhiteCrownedBishop.png"></td>
208 <td class="n" id="sq7x4" onmousedown="down_click(7,4)"
209 onmouseup="up_click()"><img src="sym/WhiteBishop.png"></td>
211 <td class="n" id="sq8x4"></td>
213 <td class="n" id="sq9x4"></td>
215 <td class="h"><img src="sym/cyan.png"></td>
217 <td class="w" rowspan="2" valign="top">Captured while passing
218 through the square to another destination</td>
222 <td class="n" id="sq0x3"></td>
224 <td class="n" id="sq1x3"><img src="sym/BlackPawn.png"></td>
226 <td class="n" id="sq2x3"></td>
228 <td class="n" id="sq3x3"></td>
230 <td class="n" id="sq4x3" onmousedown="down_click(4,-3)"
231 onmouseup="up_click()"><img src="sym/WhiteKnight.png"></td>
233 <td class="n" id="sq5x3"></td>
235 <td class="n" id="sq6x3"></td>
237 <td class="n" id="sq7x3"></td>
239 <td class="n" id="sq8x3"></td>
241 <td class="n" id="sq9x3"></td>
245 <td class="n" id="sq0x2"></td>
247 <td class="n" id="sq1x2"></td>
249 <td class="n" id="sq2x2"></td>
251 <td class="n" id="sq3x2"></td>
253 <td class="n" id="sq4x2"></td>
255 <td class="n" id="sq5x2"></td>
257 <td class="n" id="sq6x2"></td>
259 <td class="n" id="sq7x2" onmousedown="down_click(7,2)"
260 onmouseup="up_click()"><img src="sym/WhitePawn.png"></td>
262 <td class="n" id="sq8x2"></td>
264 <td class="n" id="sq9x2"></td>
268 <td class="n" id="sq0x1"></td>
270 <td class="n" id="sq1x1"></td>
272 <td class="n" id="sq2x1" onmousedown="down_click(2,1)"
273 onmouseup="up_click()"><img src="sym/WhitePawn.png"></td>
275 <td class="n" id="sq3x1"></td>
277 <td class="n" id="sq4x1"></td>
279 <td class="n" id="sq5x1"></td>
281 <td class="n" id="sq6x1"></td>
283 <td class="n" id="sq7x1"></td>
285 <td class="n" id="sq8x1"></td>
287 <td class="n" id="sq9x1"></td>
291 <td class="n" id="sq0x0"></td>
293 <td class="n" id="sq1x0"></td>
295 <td class="n" id="sq2x0"></td>
297 <td class="n" id="sq3x0"></td>
299 <td class="n" id="sq4x0"></td>
301 <td class="n" id="sq5x0"></td>
303 <td class="n" id="sq6x0"></td>
305 <td class="n" id="sq7x0"></td>
307 <td class="n" id="sq8x0"></td>
309 <td class="n" id="sq9x0"></td>
313 <p id="piece" height="20">:<br>
318 <table cellpadding="5" border="1">
326 <td>Moves (<a href="Betza.html">Betza notation</a>)</td>
340 <td>Can castle with Rook, moving 3 steps towards it</td>
350 <td>KNAD(cK-aK)(K-bK)</td>
352 <td>Can make two independent King steps per turn (capturing
353 upto two pieces)</td>
369 <td>Crowned Rook</td>
377 <td>aka Dragon Kin</td>
381 <td>Crowned Bishop</td>
389 <td>aka Dragon Horse</td>
437 <td>aka Man or Soldier</td>
449 <td>Promotes to Q, R, B, or N on reaching promotion zone</td>
453 <h3>Pawn peculiarities</h3>
456 <li>Pawns capture differently from how they move (straight
457 move, diagonal capture).</li>
459 <li>Pawns can move two squares straight ahead from their
460 initial position, provided they are not blocked.</li>
462 <li>On the move immediately after such a double push, they can
463 be captured en passant by another Pawn, as if they had only
464 moved 1 square ahead.</li>
466 <li>Pawns promote asthey promote in orthodox Chess piece of
467 choice when they enter the promotion zone (in the Chess-like
473 <p>A King that has not moved before can move <b>three</b> squares
474 in the direction of a Rook that has not moved before, in which
475 case that Rook is moved to the square the King skipped over. This
476 is only allowed if all squares between King and Rook are empty,
477 when the King is not in check on the square it came from, and
478 would not be in check on any of the squares it skipped over.</p>
480 <h3>General rules</h3>
483 <li>It is not allowed to expose your King to check.</li>
485 <li>The game is won by checkmating the opponent's King.</li>
487 <li>Stalemate (no legal moves, but not in check) is a
490 <li>The promotion zone is three ranks deep.</li>
492 <li>You cannot promote to Lion if you already have one.</li>
495 <h3>Chess-like or Shogi-like promotion</h3>
497 <p>In the Chess-like version only Pawns promote. You can choose
498 what piece to promote to, but promotion is mandatory: you cannot
499 stay a Pawn. In the Shogi-like version other pieces can also
500 promote, but there is no choice: pieces promote to their
501 'crowned' versions, and acquire the moves of a King on top of
502 their own that way. Pieces that already had all King moves cannot
503 promote. Thus a Commoner cannot Promote, and a Pawn can only
504 promote to Commoner. The Knight promotes to Lion, and thus gains
505 unusually much in value.</p>
507 <h3>The Lion piece</h3>
509 <p>The Lion can make two moves per turn. That means it can also
510 capture two pieces per turn, one on the square it moves to (as
511 normal), and one 'en passant' on the transit square. It can also
512 capture on the transit square, and move on to an empty square
513 ('hit and run'), or capture and move back to where it came from
514 ('shooting' the piece from a distance, as it were). Of course it
515 can also capture a single piece in the normal Chess manner. In
516 that case the transit square is immaterial.</p>
518 <p>The Lion can make such double moves as two King steps, i.e. in
519 all directions, and arbitrarily changing direction between them.
520 It can also jump over the transit square, i.e. reach the distant
521 two-step destination in a single jump. Finally it can also just
522 make a step to an adjacent square, refraining from taking a
525 <h3>Restrictions on Lion capture</h3>
527 <p>There are rules to make Lion trading very difficult, in order
528 to keep the Lions in play. Basically they specify that two Lions
529 cannot be captured in consecutive half-moves. When the first
530 capture is Lion x Lion from a distance, it is forbidden to play
531 it if pseudo-legal (i.e. without taking account of check)
532 recapture of the capturing Lion is possible <i>with another piece
533 than King</i>. So even when the Lion is protected only with a
534 pinned piece, the other Lion cannot capture it <i>from a
535 distance</i>, just like a King could not capture it.</p>
537 <p>When a non-Lion captures a Lion, it is just the other way
538 around: then the 'counterstrike' by a non-Lion against the Lion
539 is forbidden. One possibility left open is thus when you capture
540 an adjacent Lion. But then you would in general be foolish to
541 allow recapture, as you could take the Lion hit-and-run fashion,
542 fleeing to a save square. An exception to the rule is when a
543 valuable opponent piece (i.e. not a Pawn) forms a 'bridge'
544 between the Lions; you may then capture that piece in the first
545 leg of the double-move, and then take the opponent Lion with the
546 second leg. Then the opponent can recapture, but he will have
547 lost a valuable piece. In the late end-game, when you have
548 nothing to protect your Lion with other than King, trading
549 becomes possible.</p>
551 <h3>XBoard interface issues</h3>
553 <p>This game has to be played with the option Show Target Squares
554 on! This option will cause marking of the target squares of any
555 piece you select or grab, by the engine (with legality testing
556 off) or by XBoard (legality testing on). Moving to a square
557 marked in cyan will be interpreted not as the final destination,
558 but as the transit square after the first step of a multi-leg
559 move. XBoard will then highlight the possible destination squares
560 of the second leg from there. Should you want to end on the cyan
561 square, you click it again, (it will be no longer marked in
562 cyan), and XBoard will terminate the move after the first leg.
563 You can also move back to the starting square, to 'shoot' the
564 opponent piece from nearby.</p>
566 <p>XBoard will allow both the Chess-like and the Shogi-like
567 promotion; the engine will have to decide which promotion style
568 it thinks legal. The default choice in 'sweep-promotions' mode
569 will be deferral for pieces, however, to facilitate Chess-like
570 play. To play a Shogi promotion in this mode you should enter it
571 as a click-click move, but during the click on the promotion
572 square move the mouse pointer down until the promoted piece
573 appears, and only then release the mouse button. The Pawn will
574 show Queen as default, and a 'dragging click' on the promotion
575 square will cycle through all choices. In the Shogi version you
576 would have to choose the Commoner that way. With a promotion
577 popup you would have to press 'No' on piece moves into the zone
578 when you play the Chess-like version, and press 'Commoner' on
579 Pawn promotions when you play the Shogi-like version.</p>
581 <h3>Differences with FIDE</h3>
583 <p>The board is 10x10, with a 3-rank-deep promotion zone. The
584 initial setup leaves an almost empty rank behind the pieces,
585 where you can immediately castle. You have a Lion, Crowned Rook,
586 Crowned Bishop and two Soldiers as extra pieces. In the
587 Shogi-like version of the rules, some pieces other than Pawn can
590 <h3>Strategy issues</h3>
592 <p>It is not possible to force checkmate on a bare King with just
593 a single Bishop or Knight (in addition to your own King). Two
594 Knights cannot do that either.</p>
596 <p>With a single Commoner you can force checkmate on a bare
599 <p>Bishops are confined to squares of a single color. Having
600 Bishops on both colors compensates this weakness, and is worth an
601 extra 0.5 on top of their added value.</p>
603 <p>A Queen is upward compatible with all weaker pieces except
604 Knight. So only promotion to Queen or Knight makes sense, (except
605 perhaps for rare situations where you might have to avoid
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