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 draughts game: by jumping over its enemies,
  96     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
 100 figure.diagram-container
 101     .diagram
 102         | fen:2n2b1k/3r4/8/3p4/8/3b4/3N4/K7 w d4,d6,d8:
 103     figcaption All marked squares are playable from d2.
 104
 105 h4 Withdrawer (queen)
 106
 107 p.
 108     The queen captures by moving away from an adjacent enemy piece, in the opposite
 109     direction (only the long leaper can jump).
 110
 111 figure.diagram-container
 112     .diagram
 113         | fen:7k/8/8/3Qr3/8/8/8/K7 w a5,b5,c5:
 114     figcaption 1.Qa5, 1.Qb5 or 1.Qc5 captures the black rook.
 115
 116 h4 Chameleon (bishop)
 117
 118 p The chameleon captures pieces in the way they would capture. So, it
 119 ul
 120     li pinces pawns,
 121     li withdraws from withdrawers,
 122     li leaps over long leapers,
 123     li coordinates coordinators.
 124 p ...and these captures can be combined.
 125
 126 figure.diagram-container
 127     .diagram
 128         | fen:7k/8/8/m3pP2/2n5/8/B7/K7 w a5,c4,e5:
 129     figcaption 1.Bd5 captures all marked pieces.
 130
 131 p.
 132     Besides, chameleon immobilizes immobilizers (but cannot capture them since they
 133     do not capture).
 134
 135 p.
 136     A chameleon captures the king in the same way the king captures, which means that
 137     a chameleon adjacent to a king gives check.
 138
 139 h3 End of the game
 140
 141 p.
 142     Checkmate or stalemate as in standard chess. Note however that checks are more
 143     difficult to see, because of the exotic capturing rules. For example, on the
 144     following diagram the white king cannot move to the marked squares because then
 145     the black pawn could capture by moving next to it.
 146
 147 figure.diagram-container
 148     .diagram
 149         | fen:7k/8/8/p4r/4K3/8/8/8 w e5:
 150     figcaption 1.Ke5 is impossible
 151
 152 h3 Credits
 153
 154 p.
 155     A good starting point is the
 156     #[a(href="https://en.wikipedia.org/wiki/Baroque_chess") Wikipedia page],
 157     which also gives pointers to other interesting pages (including chessvariants.com,
 158     as usual).