views/rules/Ultima.pug

   1 p.boxed
   2     | Most pieces look the same but behave very differently.
   3     | They generally move like an orthodox queen,
   4     | but capturing rules are complex.
   5
   6 h3 Specifications
   7
   8 ul
   9     li Chessboard: standard.
  10     li Material: "standard".
  11     li Non-capturing moves: often like queen.
  12     li Special moves: none.
  13     li Captures: very special.
  14     li End of game: standard; see below.
  15
  16 h4 Pieces names
  17
  18 p Pieces names refer to the way they capture, which is described later.
  19 ul
  20     li Pawn : pawn or pincer
  21     li Rook : coordinator
  22     li Knight : long leaper
  23     li Bishop : chameleon
  24     li Queen : withdrawer
  25     li King : king (same behavior as in standard chess)
  26 p.
  27     Besides, a new piece is introduced: the immobilizer, represented by the letter 'm'
  28     in FEN diagrams and PGN games. It is represented by an upside-down rook:
  29
  30 figure.diagram-container
  31     .diagram
  32         | fen:8/8/4m3/8/8/8/3M4/8:
  33     figcaption Immobilizers on d2 and e6.
  34
  35 h3 Non-capturing moves
  36
  37 p
  38     | Pawns move as orthodox rooks, and the king moves as usual,
  39     | one square in any direction.
  40     | All other pieces move like an orthodox queen.
  41
  42 p When a piece is adjacent to an enemy immobilizer, it cannot move unless
  43 ul
  44     li it is an immobilizer or a chameleon; or
  45     li.
  46         the enemy immobilizer is adjacent to a friendly immobilizer or chameleon
  47         (cancelling the powers of the opponent's immobilizer)
  48 p
  49     | Note : this corresponds to the "pure rules" described on
  50     a(href="http://www.inference.org.uk/mackay/ultima/ultima.html") this page
  51     | , which slightly differ from the initial rules.
  52     | The aim is to get rid of the weird suicide rule, weakening the immobilizers lock
  53     | (in particular, in the original rules two adjacent immobilizer are stuck forever
  54     | until one is captured).
  55
  56 h3 Capturing moves
  57
  58 p
  59     | Easy case first: the king captures as usual, by moving onto an adjacent square
  60     | occupied by an enemy piece. But this is the only piece following orthodox rules,
  61     | and also the only one which captures by moving onto an occupied square.
  62     | All other pieces capture passively: they land on a free square and captured
  63     | units are determined by some characteristics of the movement.
  64
  65 p Note: the immobilizer does not capture.
  66
  67 h4 Pawns/Pincers
  68
  69 p.
  70     If at the end of its movement a pawn is horizontally or vertically adjacent to an
  71     enemy piece, which itself is next to a friendly piece (in the same direction),
  72     the "pinced" unit is removed from the board.
  73
  74 figure.diagram-container
  75     .diagram
  76         | fen:7k/5ppp/2N5/2n5/3rB3/8/PPP5/K7:
  77     figcaption 1.Pc2c4 captures both coordinator and long leaper.
  78
  79 h4 Coordinators (rooks)
  80
  81 p.
  82     Imagine that rook and king are two corners of a rectangle (this works if these
  83     two pieces are unaligned).
  84     If at the end of a rook move an enemy piece stands in any of the two remaining
  85     corners, it is captured.
  86
  87 figure.diagram-container
  88     .diagram
  89         | fen:8/2b4K/2q5/3p1N1p/8/8/2R5/k7:
  90     figcaption 1.Rc5 captures on c7 and h5.
  91
  92 h4 Long leapers (knights)
  93
  94 p.
  95     A knight captures exactly as a queen in international draughts game: by jumping
  96     over its enemies, as many times as it can/want but always in the same direction.
  97     In this respect it is less powerful than a draughts' queen:
  98     on the following diagram c8 or f6 cannot be captured.
  99     However, the knight does not have to maximize the number of captured units
 100     (as is the case in draughts).
 101
 102 figure.diagram-container
 103     .diagram
 104         | fen:2n4k/3r4/5b2/3p4/1m6/3b4/3N4/K7 w d4,d6,d8,a5:
 105     figcaption All marked squares captures are playable from d2.
 106
 107 h4 Withdrawer (queen)
 108
 109 p.
 110     The queen captures by moving away from an adjacent enemy piece, in the opposite
 111     direction (only the long leaper can jump).
 112
 113 figure.diagram-container
 114     .diagram
 115         | fen:7k/8/8/3Qr3/8/8/8/K7 w a5,b5,c5:
 116     figcaption 1.Qa5, 1.Qb5 or 1.Qc5 captures the black rook.
 117
 118 h4 Chameleon (bishop)
 119
 120 p The chameleon captures pieces in the way they would capture. So, it
 121 ul
 122     li pinces pawns,
 123     li withdraws from withdrawers,
 124     li leaps over long leapers,
 125     li coordinates coordinators.
 126 p ...and these captures can be combined.
 127
 128 figure.diagram-container
 129     .diagram
 130         | fen:7k/8/8/r3pP2/2n5/8/B7/K7 w a5,c4,e5:
 131     figcaption 1.Bd5 captures all marked pieces.
 132
 133 p.
 134     Besides, chameleon immobilizes immobilizers (but cannot capture them since they
 135     do not capture).
 136
 137 p.
 138     A chameleon captures the king in the same way the king captures, which means that
 139     a chameleon adjacent to a king gives check.
 140
 141 h3 End of the game
 142
 143 p.
 144     Checkmate or stalemate as in standard chess. Note however that checks are more
 145     difficult to see, because of the exotic capturing rules. For example, on the
 146     following diagram the white king cannot move to the marked squares because then
 147     the black pawn could capture by moving next to it.
 148
 149 figure.diagram-container
 150     .diagram
 151         | fen:7k/8/8/p4r/4K3/8/8/8 w e5:
 152     figcaption 1.Ke5 is impossible
 153
 154 h3 Credits
 155
 156 p.
 157     A good starting point is the
 158     #[a(href="https://en.wikipedia.org/wiki/Baroque_chess") Wikipedia page],
 159     which also gives pointers to other interesting pages (including chessvariants.com,
 160     as usual).