Dedicated to the late Richard A. Harshman

Official Rules for Three-way Chess  ("Harshman et al. variant")**[now updated to v.2.1.2]



Principles  behind points earned by each kind of victory

Kinds of thinking required and implications for human-computer competition


chess2.jpg (132816 bytes)

 Several versions of three-player chess have been developed over the last few years. This site offers a place to discuss them and to play one particular version, called "Three-Way Chess" (abbreviated TWC or 3WC). The board and initial setup are shown at right.  

Design goals: In developing this version, we have focused on optimally carrying over to three-way chess the “deep” strategic/mathematical properties of the game of chess that are important in high-level play.  At the same time we have tried to incorporate the most important and engaging new dimensions of play made possible by the presence of three players. We will post more on these objectives and how we have tried to realize them in the future, and invite discussion from players and others.

In order to play: You can (i) use your computer printer to construct a physical three-way chess set; (ii) use the java software provided on this site to display an electronic (semi-intelligent) chess board and active chess pieces; or (iii) use three computers at three different locations, each displaying "electronic" Boards which you keep manually synchronized via our chat-rooms. (And (iv) an over-the-net link that automatically synchronizes moves on the Demo Boards of all three players is under development.)

(i)  Build Your Own Chess Set: Using material from this site, you can create your own physical three-way chess set. We provide the official rules**, together with images of board and chessmen icons that you can print out (first two links below). Then, if you paste the icons onto poker chips or cardboard, you can move them around on the printed board.  For convenience, we have also created a  “Zip Pack” that contains a “kit” with all the relevant files (rules, pieces, board, a discussion of principles, and note on the “kinds of thinking” involved (third link below).   Download Printable 3wc Chessboard  and  Printable 3wc Chessmen Icons , or  Zip Pac: Build-Your-Own-3wc Set  (Zip-Pack includes Board, Men, Rules, and memos on 3wc theory ["Kinds of thinking" and "Principles behind points"].)   

(ii)  Demo Game: Using Demo Game Setup, three players can sit around a single computer and move their pieces by clicking and dragging them with a mouse. This is a good way to learn, since the moves available to any piece from its current location can be displayed by right-clicking on that piece, and illegal moves are not allowed. The Setup also allows captures, including en passant capture, as well as castling and pawn promotion. It also keeps a history of the moves, in a formal chess notation, and will display it whenever request

(iii)  Synchronized remote boards: Opponents can be located on different computers in different citie, yet play a game by keeping their boards synchronized. See play over the net.

People to play with:  If enough participate, we might post contact information on interested potential players and  groups . Players need not be near one another, since it is now possible to play over the net, and we are working on even even easier methods of doing this.

Recognizing contributors and supporters: We  have started a list of contributors and supporters to acknowledge some of the many people who have played a role in the development, refinement, and/or expert-testing of this Three-Way Chess game and its website. The list is incomplete and we invite reminders concerning others to add.

One recent source of valuable input and expert-testing has been the University of Western Ontario Chess Club.  For example, they took the 3WC game to the international Pan-American Inter-University Chess Tournament, held in Florida, December, 2003. The first row of pictures below shows some of the international competitors playing the game experimentally after tournament hours.

An international group of
chess competitors explore
three-way play after hours
3way.JPG (9586 bytes)3way1.JPG (9969 bytes)threewaychess2v2.jpg (82388 bytes) at the Pan-American Inter-
University Chess Tournament

Florida, December 2003

  Pictures courtesy UWO Chess Club


Likewise, scientists, mathematicians and their grad students have been a rich source of ideas and encouragement. In fact, the game was first officially played at an international scientific meeting, where it was introduced as part of a poster presentation.


An international group of 
scientists/mathematicians explore
three-way play after hours 
at the International conference on
Three-way statistical methods in
Chemistry and Psychology,
Kentucky, June 2003.


It seems that scientists and mathematicians continue to be intrigued, since the 3WC chessboard has been adopted (somewhat playfully) as the official logo for the next TRICAP 2006 conference on three-way methods upcoming in Crete, Greece this summer.


Chat rooms give a further way for players and others to exchange comments and ideas.  And they now can be used in a powerful new way -- to play a three-way game against distant opponents! See  how to play over the net 3WC-online

These chat rooms are also intended for discussion of various other three-way versions of Chess. We have started a list of links to these games, and will be happy to add other worthwhile entries.  So  far, our initial list includes the following:          <--  Newly listed

Other information::
Recent upgrades    Issues & Bugs
(unfixed and fixed)    En Passant clip     Castling demo    Board Coordinates (small image)   Board coordinates (large image)  

*H-variant = "Harshman et al.” variant

** A new edition of the rules (2.1) has been reviewed and posted.  No rules have changed, but some clarifications and added distinctions have been introduced, particularly concerning checkmate, stalemate, ties, and resignation. Temporarily, for the benefit of players familiar with the prior version, the additions have been highlighted in yellow. <a correction to lines 212 and 213 (reversing "Y" and "Z") and clarification of  the following lines was made April 23,2006>

     website contact: Revised: April 13, 2010