3 <title>Seirawan Chess</title>
4 <link rel=StyleSheet href="./moves.css" type="text/css">
5 <script type="text/javascript" src="spartan.js"></script>
8 <h1>Seirawan Chess (S-Chess)</h1>
9 <table cellpadding="20"><tr><td>
10 <img src="Seirawan.png">
11 <p><i>Pieces available for gating will be displayed beside the board</i></p>
13 <h3>Initial setup</h3>
21 c1, c8, f1, f8: Bishop
23 b1, b8, g1, g8: Knight
36 <h3>Moves at a Glance</h3>
38 <p>Click on a piece below to see its moves</p>
40 <table class="board"><tr><td class="h" id="0x9">
42 </td><td class="n" id="1x9" onmouseDown="down_click(1,-9)" onmouseUp="up_click()">
43 <img src="sym/BlackRook.png">
44 </td><td class="n" id="2x9">
46 </td><td class="n" id="3x9">
48 </td><td class="n" id="4x9">
50 </td><td class="n" id="5x9" onmouseDown="down_click(5,9)" onmouseUp="up_click()">
51 <img src="sym/BlackKing.png">
52 </td><td class="n" id="6x9">
54 </td><td class="n" id="7x9">
56 </td><td class="n" id="8x9" onmouseDown="down_click(8,9)" onmouseUp="up_click()">
57 <img src="sym/BlackRook.png">
58 </td><td class="h" id="9x9">
61 <img src="sym/yellow.png">
62 </td><td class="w" rowspan="2" valign="top">
63 <p>Sliding capture or non-capture,<br>can be blocked on any square along the ray</p>
64 </td></tr><tr><td class="h" id="0x8">
66 </td><td class="n" id="1x8">
68 </td><td class="n" id="2x8" onmouseDown="down_click(2,0)" onmouseUp="up_click()">
70 </td><td class="n" id="3x8">
72 </td><td class="n" id="4x8">
74 </td><td class="n" id="5x8">
76 </td><td class="n" id="6x8">
78 </td><td class="n" id="7x8">
80 </td><td class="n" id="8x8">
82 </td><td class="h" id="9x8">
84 </td></tr><tr><td class="h" id="0x7">
86 </td><td class="n" id="1x7">
88 </td><td class="n" id="2x7">
90 </td><td class="n" id="3x7">
92 </td><td class="n" id="4x7">
94 </td><td class="n" id="5x7">
96 </td><td class="n" id="6x7">
98 </td><td class="n" id="7x7">
100 </td><td class="n" id="8x7">
102 </td><td class="h" id="9x7">
105 <img src="sym/orange.png">
107 Unblockable leap (capture or non-capture)
108 </td></tr><tr><td class="h" id="0x6">
110 </td><td class="n" id="1x6">
112 </td><td class="n" id="2x6">
114 </td><td class="n" id="3x6">
116 </td><td class="n" id="4x6">
118 </td><td class="n" id="5x6" onmouseDown="down_click(5,10)" onmouseUp="up_click()">
119 <img src="sym/WhiteHawk.png">
120 </td><td class="n" id="6x6">
122 </td><td class="n" id="7x6">
124 </td><td class="n" id="8x6">
126 </td><td class="h" id="9x6">
129 <img src="sym/green.png">
132 </td></tr><tr><td class="h" id="0x5">
134 </td><td class="n" id="1x5">
136 </td><td class="n" id="2x5">
138 </td><td class="n" id="3x5">
140 </td><td class="n" id="4x5">
142 </td><td class="n" id="5x5">
144 </td><td class="n" id="6x5">
146 </td><td class="n" id="7x5">
148 </td><td class="n" id="8x5">
150 </td><td class="h" id="9x5">
153 <img src="sym/red.png">
156 </td></tr><tr><td class="h" id="0x4">
158 </td><td class="n" id="1x4">
160 </td><td class="n" id="2x4">
162 </td><td class="n" id="3x4">
164 </td><td class="n" id="4x4">
166 </td><td class="n" id="5x4" onmouseDown="down_click(-5,4)" onmouseUp="up_click()">
167 <img src="sym/WhiteElephant.png">
168 </td><td class="n" id="6x4">
170 </td><td class="n" id="7x4">
172 </td><td class="n" id="8x4">
174 </td><td class="h" id="9x4">
176 </td></tr><tr><td class="h" id="0x3">
178 </td><td class="n" id="1x3" onmouseDown="down_click(1,3)" onmouseUp="up_click()">
179 <img src="sym/BlackPawn.png">
180 </td><td class="n" id="2x3" onmouseDown="down_click(2,3)" onmouseUp="up_click()">
181 <img src="sym/WhitePawn.png">
182 </td><td class="n" id="3x3" onmouseDown="down_click(3,3)" onmouseUp="up_click()">
183 <img src="sym/WhiteRook.png">
184 </td><td class="n" id="4x3" onmouseDown="down_click(4,3)" onmouseUp="up_click()">
185 <img src="sym/WhiteKnight.png">
186 </td><td class="n" id="5x3" onmouseDown="down_click(5,3)" onmouseUp="up_click()">
187 <img src="sym/WhiteQueen.png">
188 </td><td class="n" id="6x3" onmouseDown="down_click(6,3)" onmouseUp="up_click()">
189 <img src="sym/WhiteBishop.png">
190 </td><td class="n" id="7x3" onmouseDown="down_click(7,3)" onmouseUp="up_click()">
191 <img src="sym/WhiteKing.png">
192 </td><td class="n" id="8x3">
194 </td><td class="h" id="9x3">
196 </td></tr><tr><td class="h" id="0x2">
198 </td><td class="n" id="1x2">
200 </td><td class="n" id="2x2">
202 </td><td class="n" id="3x2">
204 </td><td class="n" id="4x2">
206 </td><td class="n" id="5x2">
208 </td><td class="n" id="6x2">
210 </td><td class="n" id="7x2">
212 </td><td class="n" id="8x2">
214 </td><td class="h" id="9x2">
216 </td></tr><tr><td class="h" id="0x1">
218 </td><td class="n" id="1x1">
220 </td><td class="n" id="2x1" onmouseDown="down_click(-2,1)" onmouseUp="up_click()">
221 <img src="sym/WhitePawn.png">
222 </td><td class="n" id="3x1">
224 </td><td class="n" id="4x1">
226 </td><td class="n" id="5x1">
228 </td><td class="n" id="6x1">
230 </td><td class="n" id="7x1">
232 </td><td class="n" id="8x1">
234 </td><td class="h" id="9x1">
235 <img src="sym/WhiteElephant.png">
236 </td></tr><tr><td class="h" id="0x0">
238 </td><td class="n" id="1x0">
240 </td><td class="n" id="2x0">
242 </td><td class="n" id="3x0">
244 </td><td class="n" id="4x0">
246 </td><td class="n" id="5x0">
248 </td><td class="n" id="6x0">
250 </td><td class="n" id="7x0" onmouseDown="down_click(7,0)" onmouseUp="up_click()">
251 <img src="sym/WhiteKnight.png">
252 </td><td class="n" id="8x0">
254 </td><td class="h" id="9x0">
255 <img src="sym/WhiteHawk.png">
258 <p id="piece" height="20">:<br>:<br>:<br>:</p>
260 <table cellpadding="5" border="1"><tr><td>
267 Moves (<a href="Betza.html">Betza notation</a>)
279 Can castle with Rook, moving 3 steps towards it
349 Promotes to Q, E, H, R, B, or N on reaching last rank
351 <h3>Pawn peculiarities</h3>
353 <li>Pawns capture differently from how they move (straight move, diagonal capture).</li>
354 <li>Pawns can move two squares ahead from their initial position, provided they are not blocked.</li>
355 <li>On the move immediately after such a double push, they can be captured en passant by another Pawn,
356 as if they had only moved 1 square ahead.</li>
357 <li>Pawns promote to any other (non-royal) piece of choice when they reach last rank.</li>
361 A King that has not moved before can move <b>three</b> squares in the direction of a Rook that has not moved before,
362 in which case that Rook is moved to the square next to the King on the other side.
363 This is only allowed if all squares between King and Rook are empty,
364 when the King is not in check on the square it came from,
365 and would not be in check on any of the squares it skipped over.
367 <h3>General rules</h3>
369 <li>It is not allowed to expose your King to check.</li>
370 <li>The game is won by checkmating the opponent's King.</li>
371 <li>Stalemate (no legal moves, but not in check) is a draw.</li>
372 <li>The Elephant or Hawk can be 'gated' into play, by placing them on a square evacuated by a back-rank piece
373 that moved for the first time, as second part of the same turn.</li>
374 <li>During gating, your King must not 'pass through check'.</li>
375 <li>When castling, you can gate onto the King or Rook square, but not on both.</li>
377 <h3>XBoard interface issues</h3>
379 To perform a gating move, first select the piece to be gated.
380 (When you have not switched off highlighting or the line gap, this will draw a yellow border around the piece.)
381 Then move the piece on the back rank.
382 If you drag the piece, the gated piece will appear from under it.
383 (With click-click moving you will only see it after the move is already done.)
384 To gate on the Rook square after castling, you have to enter the castling by dragging the Rook onto the King!
387 To enter a gating move by typing, you have to suffix them with /H or /E.
388 For gating on the Rook square after castling, you would have to write the castling as RxK.
389 (Ughh! Good thing that no one in his right mind would want to gate there!)
391 <h3>Differences with FIDE</h3>
393 The Elephant and Hawk pieces are extra, and enter the board by gating.
395 <h3>Strategy issues</h3>
397 It is not possible to force checkmate on a bare King with just a single Bishop or Knight (in addition to your own King).
398 Two Knights cannot do that either.
399 The Archbishop can force checkmate against a bare King.
402 Bishops are confined to squares of a single color.
403 Having Bishops on both colors compensates this weakness, and is worth an extra 0.5 on top of their added value.
406 As Elephant and Hawk are nearly equal in value to Queen, under-promotion is very common.
409 The super-pieces (Q, E, H) devaluate by the presence of lower-valued opponent pieces.
410 As a result trading Q for R + B is in general a good trade when you still have E and H,
411 as the latter gain in value by eliminating the opponent's R and B,
412 which is more compensation than the intrinsic value difference between Q and R + B.
415 Keeping E and H in hand is good if there are still many gating opportunities,
416 as you can then gate at the location that is most damaging to your opponents position.
417 When there are not too many positions left, protecting the remaining ones becomes a vulnerability, however,
418 so you better use them were you still can.
419 If you still have a piece in hand, and only a single Knight that can gate it (bacause all your other pieces already moved),
420 even sacrificing a Queen for that Knight would gain your opponent a piece.