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.
  43     When a piece is adjacent to an enemy immobilizer, it cannot move unless
  44     the enemy immobilizer is adjacent to a friendly immobilizer or chameleon
  45     (cancelling the powers of the opponent's immobilizer).
  46 p
  47     | Note : this corresponds to the "pure rules" described on
  48     a(href="http://www.inference.org.uk/mackay/ultima/ultima.html") this page
  49     | , which slightly differ from the initial rules.
  50     | The aim is to get rid of the weird suicide rule by weakening the immobilizers lock.
  51     | In particular, in the original rules two adjacent immobilizer are stuck forever
  52     | until one is captured. Note that it's still the case if all chameleons disappeared.
  53
  54 h3 Capturing moves
  55
  56 p
  57     | Easy case first: the king captures as usual, by moving onto an adjacent square
  58     | occupied by an enemy piece. But this is the only piece following orthodox rules,
  59     | and also the only one which captures by moving onto an occupied square.
  60     | All other pieces capture passively: they land on a free square and captured
  61     | units are determined by some characteristics of the movement.
  62
  63 p Note 1: the immobilizer does not capture.
  64
  65 p.
  66     Note 2: for passive captures, a 'X' is added at the end of the move notation,
  67     to indicate that something was taken (replaying the game is necessary to know where).
  68
  69 h4 Pawns/Pincers
  70
  71 p.
  72     If at the end of its movement a pawn is horizontally or vertically adjacent to an
  73     enemy piece, which itself is next to a friendly piece (in the same direction),
  74     the "pinced" unit is removed from the board.
  75
  76 figure.diagram-container
  77     .diagram
  78         | fen:7k/5ppp/2N5/2n5/3rB3/8/PPP5/K7:
  79     figcaption 1.Pc2c4 captures both coordinator and long leaper.
  80
  81 h4 Coordinators (rooks)
  82
  83 p.
  84     Imagine that rook and king are two corners of a rectangle (this works if these
  85     two pieces are unaligned).
  86     If at the end of a rook move an enemy piece stands in any of the two remaining
  87     corners, it is captured.
  88
  89 figure.diagram-container
  90     .diagram
  91         | fen:8/2b4K/2q5/3p1N1p/8/8/2R5/k7:
  92     figcaption 1.Rc5 captures on c7 and h5.
  93
  94 h4 Long leapers (knights)
  95
  96 p.
  97     A knight captures exactly as a queen in international draughts game: by jumping
  98     over its enemies, as many times as it can/want but always in the same direction.
  99     In this respect it is less powerful than a draughts' queen:
 100     on the following diagram c8 or f6 cannot be captured.
 101     However, the knight does not have to maximize the number of captured units
 102     (as is the case in draughts).
 103
 104 figure.diagram-container
 105     .diagram
 106         | fen:2n4k/3r4/5b2/3p4/1m6/3b4/3N4/K7 w d4,d6,d8,a5:
 107     figcaption All marked squares captures are playable from d2.
 108
 109 h4 Withdrawer (queen)
 110
 111 p.
 112     The queen captures by moving away from an adjacent enemy piece, in the opposite
 113     direction (only the long leaper can jump).
 114
 115 figure.diagram-container
 116     .diagram
 117         | fen:7k/8/8/3Qr3/8/8/8/K7 w a5,b5,c5:
 118     figcaption 1.Qa5, 1.Qb5 or 1.Qc5 captures the black rook.
 119
 120 h4 Chameleon (bishop)
 121
 122 p The chameleon captures pieces in the way they would capture. So, it
 123 ul
 124     li pinces pawns,
 125     li withdraws from withdrawers,
 126     li leaps over long leapers,
 127     li coordinates coordinators.
 128 p ...and these captures can be combined.
 129
 130 figure.diagram-container
 131     .diagram
 132         | fen:7k/8/8/r3pP2/2n5/8/B7/K7 w a5,c4,e5:
 133     figcaption 1.Bd5 captures all marked pieces.
 134
 135 p.
 136     Besides, chameleon immobilizes immobilizers (but cannot capture them since they
 137     do not capture).
 138
 139 p.
 140     A chameleon captures the king in the same way the king captures, which means that
 141     a chameleon adjacent to a king gives check.
 142
 143 h3 End of the game
 144
 145 p.
 146     Checkmate or stalemate as in standard chess. Note however that checks are more
 147     difficult to see, because of the exotic capturing rules. For example, on the
 148     following diagram the white king cannot move to the marked squares because then
 149     the black pawn could capture by moving next to it.
 150
 151 figure.diagram-container
 152     .diagram
 153         | fen:7k/8/8/p4r/4K3/8/8/8 w e5:
 154     figcaption 1.Ke5 is impossible
 155
 156 h3 Credits
 157
 158 p.
 159     A good starting point is the
 160     #[a(href="https://en.wikipedia.org/wiki/Baroque_chess") Wikipedia page],
 161     which also gives pointers to other interesting pages (including chessvariants.com,
 162     as usual).