Zillions of Games is a commercial general game playing system developed by Jeff Mallett and Mark Lefler in 1998. The game rules are specified with S-expressions in the Zillions rule language. It was designed to handle mostly abstract strategy board games or puzzles.
After parsing the rules of the game, the system’s artificial intelligence can automatically play one or more players. It treats puzzles as solitaire games and its AI can be used to solve them.
Home http://www.zillions-of-games.com/
Wiki https://en.wikipedia.org/wiki/Zillions_of_Games
Chess variants https://www.chessvariants.com/programs.dir/zillions/
The game is written in C++ for Windows desktop (GDI) exclusively. Source code has not been released.
Here is Zillions code for Tic-Tac-Toe.
(game
(title "Tic-Tac-Toe")
(description "The game is played on a 3 by 3 grid between players X and O.
Player X goes first. Each player alternately drops a man in an empty square.
The game is won if either side gets three in a row, horizontally,
vertically, or diagonally. Otherwise it's a draw.")
(history "Tic-Tac-Toe is an old game and is often played when there are
no moveable pieces available, by drawing or carving marks.
It is played all over the world under various names, such as 'Noughts and Crosses' in
England.")
(strategy "With perfect play, Tic-Tac-Toe is a draw. First player has the
advantage, provided the first move is centre or corner. Most games are won
by leaving two open twos that cannot both be blocked.")
(players X O)
(turn-order X O)
(board
(image "TTTbrd.png")
(grid
(start-rectangle 16 16 112 112) ; top-left position
(dimensions
("A-/B-/C-" (0 112)) ; rows
("1/2/3" (112 0))) ; columns
(directions (n -1 0) (e 0 1) (nw -1 -1) (ne -1 1))
)
)
(piece
(name man)
(help "Man: drops on any empty space")
(image X "TTTX.png"
O "TTTO.png")
(drops ((verify empty?) add))
)
(board-setup
(X (man off 5))
(O (man off 5))
)
(draw-condition (X O) stalemated)
(win-condition (X O)
(or (relative-config man n man n man)
(relative-config man e man e man)
(relative-config man ne man ne man)
(relative-config man nw man nw man)
)
)
)