3 <title>Janus Chess</title>
4 <link rel=StyleSheet href="./moves.css" type="text/css">
5 <script type="text/javascript" src="spartan.js"></script>
9 <table cellpadding="20"><tr><td>
12 <h3>Initial setup</h3>
22 d1, d8, g1, g8: Bishop
24 c1, c8, h1, h8: Knight
30 <h3>Moves at a Glance</h3>
32 <p>Click on a piece below to see its moves</p>
34 <table class="board"><tr><td class="n" id="0x9" onmouseDown="down_click(2,9)" onmouseUp="up_click()">
35 <img src="sym/BlackRook.png">
36 </td><td class="n" id="1x9">
38 </td><td class="n" id="2x9">
40 </td><td class="n" id="3x9">
42 </td><td class="n" id="4x9" onmouseDown="down_click(-4,9)" onmouseUp="up_click()">
43 <img src="sym/BlackKing.png">
44 </td><td class="n" id="5x9">
46 </td><td class="n" id="6x9">
48 </td><td class="n" id="7x9">
50 </td><td class="n" id="8x9">
52 </td><td class="n" id="9x9" onmouseDown="down_click(-9,9)" onmouseUp="up_click()">
53 <img src="sym/BlackRook.png">
55 <img src="sym/yellow.png">
56 </td><td class="w" rowspan="2" valign="top">
57 <p>Sliding capture or non-capture,<br>can be blocked on any square along the ray</p>
58 </td></tr><tr><td class="n" id="0x8">
60 </td><td class="n" id="1x8">
62 </td><td class="n" id="2x8">
64 </td><td class="n" id="3x8">
66 </td><td class="n" id="4x8">
68 </td><td class="n" id="5x8">
70 </td><td class="n" id="6x8">
72 </td><td class="n" id="7x8">
74 </td><td class="n" id="8x8">
76 </td><td class="n" id="9x8">
78 </td></tr><tr><td class="n" id="0x7">
80 </td><td class="n" id="1x7">
82 </td><td class="n" id="2x7">
84 </td><td class="n" id="3x7">
86 </td><td class="n" id="4x7">
88 </td><td class="n" id="5x7">
90 </td><td class="n" id="6x7">
92 </td><td class="n" id="7x7">
94 </td><td class="n" id="8x7">
96 </td><td class="n" id="9x7">
99 <img src="sym/orange.png">
101 Unblockable leap (capture or non-capture)
102 </td></tr><tr><td class="n" id="0x6">
104 </td><td class="n" id="1x6">
106 </td><td class="n" id="2x6">
108 </td><td class="n" id="3x6">
110 </td><td class="n" id="4x6">
112 </td><td class="n" id="5x6" onmouseDown="down_click(-5,-6)" onmouseUp="up_click()">
113 <img src="sym/WhiteArchbishop.png">
114 </td><td class="n" id="6x6">
116 </td><td class="n" id="7x6">
118 </td><td class="n" id="8x6">
120 </td><td class="n" id="9x6">
123 <img src="sym/green.png">
126 </td></tr><tr><td class="n" id="0x5">
128 </td><td class="n" id="1x5">
130 </td><td class="n" id="2x5">
132 </td><td class="n" id="3x5">
134 </td><td class="n" id="4x5">
136 </td><td class="n" id="5x5">
138 </td><td class="n" id="6x5">
140 </td><td class="n" id="7x5">
142 </td><td class="n" id="8x5">
144 </td><td class="n" id="9x5">
147 <img src="sym/red.png">
150 </td></tr><tr><td class="n" id="0x4">
152 </td><td class="n" id="1x4">
154 </td><td class="n" id="2x4">
156 </td><td class="n" id="3x4">
158 </td><td class="n" id="4x4">
160 </td><td class="n" id="5x4">
162 </td><td class="n" id="6x4">
164 </td><td class="n" id="7x4">
166 </td><td class="n" id="8x4">
168 </td><td class="n" id="9x4">
170 </td></tr><tr><td class="n" id="0x3">
172 </td><td class="n" id="1x3" onmouseDown="down_click(1,3)" onmouseUp="up_click()">
173 <img src="sym/BlackPawn.png">
174 </td><td class="n" id="2x3" onmouseDown="down_click(2,3)" onmouseUp="up_click()">
175 <img src="sym/WhitePawn.png">
176 </td><td class="n" id="3x3" onmouseDown="down_click(3,3)" onmouseUp="up_click()">
177 <img src="sym/WhiteRook.png">
178 </td><td class="n" id="4x3" onmouseDown="down_click(4,3)" onmouseUp="up_click()">
179 <img src="sym/WhiteKnight.png">
180 </td><td class="n" id="5x3" onmouseDown="down_click(5,3)" onmouseUp="up_click()">
181 <img src="sym/WhiteQueen.png">
182 </td><td class="n" id="6x3" onmouseDown="down_click(6,3)" onmouseUp="up_click()">
183 <img src="sym/WhiteBishop.png">
184 </td><td class="n" id="7x3" onmouseDown="down_click(7,3)" onmouseUp="up_click()">
185 <img src="sym/WhiteKing.png">
186 </td><td class="n" id="8x3">
188 </td><td class="n" id="9x3">
190 </td></tr><tr><td class="n" id="0x2">
192 </td><td class="n" id="1x2">
194 </td><td class="n" id="2x2">
196 </td><td class="n" id="3x2">
198 </td><td class="n" id="4x2">
200 </td><td class="n" id="5x2">
202 </td><td class="n" id="6x2">
204 </td><td class="n" id="7x2">
206 </td><td class="n" id="8x2">
208 </td><td class="n" id="9x2">
210 </td></tr><tr><td class="n" id="0x1">
212 </td><td class="n" id="1x1">
214 </td><td class="n" id="2x1" onmouseDown="down_click(-2,1)" onmouseUp="up_click()">
215 <img src="sym/WhitePawn.png">
216 </td><td class="n" id="3x1">
218 </td><td class="n" id="4x1">
220 </td><td class="n" id="5x1">
222 </td><td class="n" id="6x1">
224 </td><td class="n" id="7x1">
226 </td><td class="n" id="8x1">
228 </td><td class="n" id="9x1">
230 </td></tr><tr><td class="n" id="0x0">
232 </td><td class="n" id="1x0">
234 </td><td class="n" id="2x0">
236 </td><td class="n" id="3x0">
238 </td><td class="n" id="4x0">
240 </td><td class="n" id="5x0">
242 </td><td class="n" id="6x0">
244 </td><td class="n" id="7x0">
246 </td><td class="n" id="8x0">
248 </td><td class="n" id="9x0">
252 <p id="piece" height="20">:<br>:<br>:<br>:</p>
254 <table cellpadding="5" border="1"><tr><td>
261 Moves (<a href="Betza.html">Betza notation</a>)
273 Can castle with Rook, moving 3 or 4 steps to b- or i-file
333 Promotes to Q, J, R, B, or N on reaching last rank
335 <h3>Pawn peculiarities</h3>
337 <li>Pawns capture differently from how they move (straight move, diagonal capture).</li>
338 <li>Pawns can move two squares ahead from their initial position, provided they are not blocked.</li>
339 <li>On the move immediately after such a double push, they can be captured en passant by another Pawn,
340 as if they had only moved 1 square ahead.</li>
341 <li>Pawns promote to another (non-royal) piece of choice when they reach last rank.</li>
345 A King that has not moved before can move <b>to the square neighboring</b> a Rook that has not moved before,
346 in which case that Rook is moved to the square next to the King on the other side.
347 This is only allowed if all squares between King and Rook are empty,
348 when the King is not in check on the square it came from,
349 and would not be in check on any of the squares it skipped over.
351 <h3>General rules</h3>
353 <li>It is not allowed to expose your King to check.</li>
354 <li>The game is won by checkmating the opponent's King.</li>
355 <li>Stalemate (no legal moves, but not in check) is a draw.</li>
357 <h3>Differences with FIDE</h3>
359 The Janus pieces are extra, and the board is expanded to accomodate them.
360 The King starts on the other side of the Queen.
361 Castling is asymmetric; the King moves 4 steps on long castling, 3 steps on short.
363 <h3>Strategy issues</h3>
365 It is not possible to force checkmate on a bare King with just a single Bishop or Knight (in addition to your own King).
366 Two Knights cannot do that either.
367 The Janus can force checkmate against a bare King.
370 Bishops are confined to squares of a single color.
371 Having Bishops on both colors compensates this weakness, and is worth an extra 0.5 on top of their added value.
374 As Janus is nearly equal in value to Queen, under-promotion to it is common,
375 and there is virtually never any need to promote to R, B or N.
378 The super-pieces (Q, J) devaluate by the presence of lower-valued opponent pieces.
379 As a result trading Q for R + B is in general a good trade when you still have both J,
380 as the latter gain in value by eliminating the opponent's R and B,
381 which is more compensation than the intrinsic value differene between Q and R + B.