Rules of MinitChess

Here are brief rules for MinitChess (aka MiniChess 2011), the MiniChess game we will build an adversary for. MinitChess is a simpler[!] version of Speed Chess.

  • The game is played on a 5x6 board

    .....
    .....
    .....
    .....
    .....
    .....
    

    As expected, the columns will be labeled a, b, c, d, e and the rows (from bottom) 1, 2, 3, 4, 5, 6. Thus, each square has a coordinate.

  • The pieces are the King (K), Queen (Q), Bishop (B), Knight (N), Rook (R) and Pawn (P).

  • The two players are White and Black. We will show white pieces as capital letters (KQBNRP) and black pieces as small letters (kqbnrp). White moves first.

  • The pieces start on the board like this:

    kqbnr
    ppppp
    .....
    .....
    PPPPP
    RNBQK
    
  • The pieces move like this:

    • The King can move one space N, S, E, W, NE, NW, SE or SW.

      .....
      xx...
      Kx...
      xx...
      .....
      .....
      
    • The Queen can move as far as she wants N, S, E, W, NE, NW, SE or SW, as long as no piece is in the way.

      x.x..
      xx...
      QxxB.
      xx...
      x.x..
      x..x.
      
    • The Rook can move as far as it wants N, S, E or W, as long as no piece is in the way.

      x....
      x....
      Rxxxx
      x....
      B....
      .....
      
    • The Bishop can move as far as he wants NE,SE,NW or SW, as long as no piece is in the way. The Bishop can instead move N, S, E, or W to an adjacent space, as long as there is no piece of either color in that space (thus, a bishop cannot capture N, S, E, or W).

      ..x..
      xx...
      Bx...
      rx...
      ..R..
      .....
      
    • The Knight moves two spaces N,S,E or W, then one space perpendicular to its previous move. It can jump over pieces in the way.

      .x...
      ..x..
      NB...
      PPx..
      .x...
      .....
      
    • The White Pawn moves one space N. The Black Pawn moves one space S. Pawns are blocked by pieces in their way. A Pawn reaching the far end of the board becomes a Queen. Pawn promotion to Queen happens even if there are other Queens of that color already; in theory six Queens of a given color could be on the board simultaneously.

      .....
      .....
      p....
      x....
      .....
      .....
      
  • Except for Pawns, a piece captures by moving onto an opposing piece. White pawns capture only by moving onto a piece NW or NE; Black pawns SW or SE.

    .....
    .....
    p....
    .x...
    .....
    .....
    
  • Victory conditions:

    • The first player to capture the opponent's King wins.

    • A game lasting more than 40 moves (by each side) is a draw.

    • If a player has no legal move on their turn, that player loses. Note that in mini-chess there is no rule against "moving into check": allowing your King to be captured is a legal move.

      In this position, Black must move its King (and then should lose the game).

      20 B
      k.K..
      rpP..
      pP...
      P....
      .....
      .....
      

      In this (very artificial) position, White loses by rule because White cannot move any piece.

      20 W
      KBk..
      PRP..
      .P...
      .....
      .....
      .....
      

If you have played chess before, this game is easy to understand. The changes from normal chess are:

  • Fewer pieces, smaller board (obviously)

  • Win by King capture

  • It is legal to move "into check"

  • No draw by repetition

  • No draw by moves after capture

  • Loss by lack of legal moves

  • Draw by total moves

  • No "castling"

  • Bishops can change color by moving into an adjacent empty space

  • Pawns always move forward one space, never two

  • Pawn promotion is always to a Queen