08feb07abu
(c) Software Lab. Alexander Burger


         Pico Lisp Demo Games
         ====================

This directory contains a few simple games. They are neither especially
interesting, nor powerful, but may be useful as programming examples.



'mine' is a simplified version of the minesweeper game. You can start it as:

$ ./p dbg.l games/mine.l -main -go

It will display a 12-by-12 field with 24 (default) hidden mines. You can move
around using the standard 'vi'-keys 'j' (down), 'k' (up), 'l' (right) and 'h'
(left).

Hit ENTER or SPACE to uncover a field, and ESC to terminate the game. In the
latter case (of if a mine exploded), you'll get the Pico Lisp prompt. Then you
can continue the game with

: (go)

possibly aftre re-initializing it with

: (main)

or exit the Pico Lisp interpreter with ENTER.



'nim' and 'ttt' are only testbeds for the general 'game' alpha-beta search
function (normally, these games are better implemented by directly exploring
their underlying principles and strategies).

Start 'nim' as

$ ./p dbg.l games/nim.l

and then find the the optimal move path for, let's say, three heaps of four
matches each:

: (nim 4 4 4)
-> (-100 ((1 . 4) 1 . -4) ((2 . 4) 2 . -4) ((3 . 4) 3 . -4))

This is a winning position (a minimal cost of -100), with three moves (in the
CARs of the move list: Take 4 from heap 1, then 4 from heap 2, and finally 4
from heap 3).



To play Tic-Tac-Toe, enter

$ ./p dbg.l games/ttt.l -main

A three-by-three board is displayed. Enter your moves with the 'go' function:

: (go a 1)
   +---+---+---+
 3 |   |   |   |
   +---+---+---+
 2 |   |   |   |
   +---+---+---+
 1 | T |   |   |
   +---+---+---+
     a   b   c

Your positions are marked with 'T', the computer's with '0'.



The 'chess' game is minimalistic (440 lines of code). Nevertheless, it plays
some slow - though correct - chess. Start it as:

$ ./p dbg.l games/chess.l -main
   +---+---+---+---+---+---+---+---+
 8 |<R>|<N>|<B>|<Q>|<K>|<B>|<N>|<R>|
   +---+---+---+---+---+---+---+---+
 7 |<P>|<P>|<P>|<P>|<P>|<P>|<P>|<P>|
   +---+---+---+---+---+---+---+---+
 6 |   | - |   | - |   | - |   | - |
   +---+---+---+---+---+---+---+---+
 5 | - |   | - |   | - |   | - |   |
   +---+---+---+---+---+---+---+---+
 4 |   | - |   | - |   | - |   | - |
   +---+---+---+---+---+---+---+---+
 3 | - |   | - |   | - |   | - |   |
   +---+---+---+---+---+---+---+---+
 2 | P | P | P | P | P | P | P | P |
   +---+---+---+---+---+---+---+---+
 1 | R | N | B | Q | K | B | N | R |
   +---+---+---+---+---+---+---+---+
     a   b   c   d   e   f   g   h

The pieces are indicated by the letters 'K'ing, 'Q'ueen, 'R'ook, 'B'ishop,
k'N'ight and 'P'awn, with black pieces in angular brackets.

Enter your moves with the field names (in lower case) for the "from" and "to"
positions:

: (go e2 e4)

Castling may be entered by just specifying the king's move:

: (go e1 g1)

To undo one or several moves, enter

: (go -)

and to redo them

: (go +)

To switch sides (and have the computer play against itself), call 'go' without
arguments:

: (go)

The initial board position can be restored with

: (main)

The global variable '*Depth' holds the maximal depth of the alpha-beta tree
search. It defaults to 5. You may change it to some smaller value for a faster
response, or to a larger value for a deeper search:

: (setq *Depth 7)

The same effect can be achieved by passing the desired depth as the first
argument to 'main':

: (main 7)

The second (optional) argument to 'main' is your color ('NIL' for white and 'T'
for black).

To setup some given board position, call 'main' with a list of triples, with
each describing:

   1. The field
   2. The piece's classes
   3. An optional flag to indicate that the piece did not move yet

: (main 5 NIL
   (quote
      (a2 (+White +Pawn) T)
      (b1 (+White +King))
      (d4 (+Black +King)) ) )
   +---+---+---+---+---+---+---+---+
 8 |   | - |   | - |   | - |   | - |
   +---+---+---+---+---+---+---+---+
 7 | - |   | - |   | - |   | - |   |
   +---+---+---+---+---+---+---+---+
 6 |   | - |   | - |   | - |   | - |
   +---+---+---+---+---+---+---+---+
 5 | - |   | - |   | - |   | - |   |
   +---+---+---+---+---+---+---+---+
 4 |   | - |   |<K>|   | - |   | - |
   +---+---+---+---+---+---+---+---+
 3 | - |   | - |   | - |   | - |   |
   +---+---+---+---+---+---+---+---+
 2 | P | - |   | - |   | - |   | - |
   +---+---+---+---+---+---+---+---+
 1 | - | K | - |   | - |   | - |   |
   +---+---+---+---+---+---+---+---+
     a   b   c   d   e   f   g   h

At any time, you can print the current board position in the above format to a
file with

: (ppos "file")

which later can be restored with

: (load "file")



There is also a plain 'sudoku' solver:

$ ./p dbg.l games/sudoku.l

: (main
   (quote
      (5 3 0 0 7 0 0 0 0)
      (6 0 0 1 9 5 0 0 0)
      (0 9 8 0 0 0 0 6 0)
      (8 0 0 0 6 0 0 0 3)
      (4 0 0 8 0 3 0 0 1)
      (7 0 0 0 2 0 0 0 6)
      (0 6 0 0 0 0 2 8 0)
      (0 0 0 4 1 9 0 0 5)
      (0 0 0 0 8 0 0 7 9) ) )
   +---+---+---+---+---+---+---+---+---+
 9 | 5   3     |     7     |           |
   +   +   +   +   +   +   +   +   +   +
 8 | 6         | 1   9   5 |           |
   +   +   +   +   +   +   +   +   +   +
 7 |     9   8 |           |     6     |
   +---+---+---+---+---+---+---+---+---+
 6 | 8         |     6     |         3 |
   +   +   +   +   +   +   +   +   +   +
 5 | 4         | 8       3 |         1 |
   +   +   +   +   +   +   +   +   +   +
 4 | 7         |     2     |         6 |
   +---+---+---+---+---+---+---+---+---+
 3 |     6     |           | 2   8     |
   +   +   +   +   +   +   +   +   +   +
 2 |           | 4   1   9 |         5 |
   +   +   +   +   +   +   +   +   +   +
 1 |           |     8     |     7   9 |
   +---+---+---+---+---+---+---+---+---+
     a   b   c   d   e   f   g   h   i

Type

: (go)

to let it search for a solution.
