Ubuntu Manpage: morris - Nine Men's Morris game for the Gnome desktop

name
synopsis
description
features
standard rules
rule details and game variations
ai algorithm
see also

NAME

       morris -  Nine Men's Morris game for the Gnome desktop

SYNOPSIS

       morris

DESCRIPTION

       Morris  is an implementation of the board game "Nine Men's Morris". Other names for this game are: Mills,
       Merrills, Morris, or Mühle in German. Nine Men's Morris, being probably 2000-3000 years old,  appears  to
       be  one  of  the oldest board games, much older than chess. From the 12th to the 18th century, Nine Men's
       Morris was one of the most popular board games in Europe. However, it is still actively played today  and
       exists in several variants, e.g., Morabaraba, which is particularly popular in South Africa.

       This  implementation  of  Nine  Men's  Morris supports not only the standard game, but also several rule-
       variants and different board layouts. You can play against the computer, or simply  use  the  program  to
       present  the  board,  but play against another human opponent. The computer opponent learns from previous
       games and tries not to make the same mistake twice. This ensures enough variation  in  game-play,  should
       you once have managed to beat the program.

FEATURES

       Among others, the game plays the following variants:

           - Lasker variant (moves are also allowed in the set-phase)

           - The Möbius board (invented by Ingo Althöfer)

           - The Windmill board

           - The Windmill board

           - Pentagon and Hexagon boards

           - Morabaraba

           - Six and Seven Men's Morris

           - Tapatan, Achi, Nine Holes

       Furthermore, the game supports:

           - Advanced AI controls to tweak AI playing style

           - Giving hints for good moves

           - Showing the principal variation

           - Move takeback (undo and redo)

           - Internationalization (English, German, Chinese)

           - Many board and rule variations

           - Free customization of rules

           - Configurable display

STANDARD RULES

Each player has nine pieces (hence the name, Nine Men's Morris) which are placed and moved on the line
crossings of the board. Whenever three pieces of the same color are placed in a straight row, a mill is
closed and one opponent piece may be removed. The goal of the game is to reduce the opponent to only two
pieces (such that he cannot form a mill anymore), or to surround the opponent pieces in such a way that
there are no valid moves for the opponent.

The game proceeds in three distinct phases (opening, midgame, and endgame). Unlike chess, these phases
are distinguished by special rules for each phase.

Opening - Setting pieces
The white player begins. Each player places one piece on an unoccupied position on the board in
turns. If a mill is closed by setting a piece, the player may take one of the opponent's pieces.
Once all pieces are set, the midgame starts.

Midgame - Moving pieces
Each player moves one piece along the lines to a free, neighboring position. Again, if the move
results in closing a mill, one of the opponent's pieces may be removed. Note that a player must
move a piece in each turn. If there is no legal move, the player has lost.

Endgame - Flying
If a player has only three pieces left, he my jump (or fly) with one piece to any unoccupied
position instead of moving only along the board lines.

RULE DETAILS AND GAME VARIATIONS

       Some  of  these rules are often interpreted differently, such that a variety of rule variants exist. This
       game tries to support most of them. In particular, the following rule variations are supported:

       Taking from opponent mills
              When a mill is closed, one opponent stone may be taken. However, usually, it  is  not  allowed  to
              take  a  piece from an opponent's mill, if he still has pieces that are not part of a mill. If you
              want, you can also allow players to take pieces from an opponent's mill. Note that you can  always
              take pieces from an opponent's mill, if all of his pieces are within mills.

       Multiple mills
              In  the  setting  phase,  it may happen that two mills are closed simultaneously. In the multiple-
              mills variations, the player may take two opponent pieces, in this case.

       Flying Some people prefer to omit the flying rule, such that only standard moves may be  conducted,  even
              when a player is down to only three pieces.

       Lasker variant (proposed by the chess grandmaster Emanuel Lasker)
              There  is  no  difference  between  opening and midgame. I.e., a player may decide to move a piece
              instead of setting a new piece. Usually, this variant is played with 10 pieces instead of only 9.

       Remis  If the same board situation appeared for N times (with N usually 3), the game is declared remis.

AI ALGORITHM

        The AI algorithm is a standard alpha-beta search in a NegaMax implementation using iterative  deepening.
       It employs a transposition table to quickly find previously computed positions.

       A  special  feature  is the automatic learning capability: whenever the computer wins or loses a game, it
       will prefer to obtain or avoid similar situations in the future.  This  results  in  a  better  long-term
       motivation,  since  the  computer  will  not  make  the  same mistake twice and the gameplay will be more
       randomized.

       The evaluation function is still quite basic and consists of four parts:

       Material
              The number of pieces each player has left

       Freedom
              The number of possible moves a player can conduct

       Mills  The number of closed mills

       Experience
              The learning-bias from previous games.