In the early 1990s, influenced by my recent discovery of Robert Abbott's Ultima, I invented several chess variants that used differently-capturing pieces. The most interesting of these was Optima, a game in which players used 10 pieces chosen from a pool of 20, ensuring that each game was different and that relative piece values were not necessarily constant. When the program Zillions-of-Games came out, I realized that I finally had a chance to playtest Optima. In the process of learning Zillions language and implementing Optima, I revised the rules, adding new pieces to the pool and balancing the game by adding guards, a unit intermediate in power between pawns and pieces. The result, I hope, is a game that is both tactical and positional, with difficult and interesting decisions regarding piece exchanges, and virtually infinite in its combinational possibilities. But all of that, of course, is for the players to judge.
 
Board:
Optima is played on a checkered board 10 squares wide and 10 squares deep.
 
Goal:
To win, a player must checkmate or stalemate the opposing king. A threefold repetition of a given position is a draw.
 
Initial Position:
Each player has 10 pawns on his third rank, 10 guards on his second rank, and 10 pieces, one of which is the king, off the board.
 
Piece sets:
In the equal-forces game, each player has the same 10 pieces, one of which is the king.
In the unequal-forces game, each player has a king, and 18 additional pieces are selected and form a "pool" belonging to both players until the placement phase is complete.
 
Placement:
Equal-forces: starting with white, each player in turn places one of his pieces on his first rank until it is full. White then makes the first move of the movement phase.
Unequal-forces: All placement is to each player's first rank. White places his king. Black then places his king and selects and places one piece from the pool. Players then alternate placing two pieces from those remaining in the pool. Placement ends with white placing the last remaining piece and then making the first move of the movement phase.
 
Pawns:
By default, pawns move one or two squares in the four orthogonal directions, and capture one square in the four diagonal directions. A pawn that reaches the 10th rank must promote to a Wizard, which is the most powerful piece in the game and is only available by pawn promotion.
Players who wish to use other pawn rules may, by agreement, change to another of the allowed pawn definitions. To do this in Zillions, they will have to manually edit the zrf file.
 
Guards:
By default, a guard moves and captures one or two squares in any direction. Guards do not promote. Players who wish to use other guard rules may, by agreement, select another of the allowed guard definitions. To do this in Zillions, they will have to manually edit the zrf file.
 
Pieces:
The other pieces move and capture as explained in OptimaReadMe.txt included in the download.
The pieces have a wide variety of powers, some of which are negated by certain piece attributes.