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How to play Bookie Chess

  1. Bookie Chess uses a cgi script to generate a chess position and to display the board in HTML. The script can be activated by clicking the "play the game" button on the navigation bar at the top or bottom of this page.
  2. In the first stage of the game, pawns and kings are hidden. Two players estimate (or "bid"), secretly and in writing, the probability, in percent, of each color winning the game given this incomplete information. The players then reveal their estimates. Whichever player bid higher on white plays white. The other player plays black.

    For example, if Adam bids 87 on white and 13 on black, and Barb bids 65 on white and 35 on black, then Adam will play white and Barb will play black.

  3. After bidding, the players click on the button on the web page labeled "Reveal pawns and kings." Then, using a standard chess board and two complete sets of pieces, they set up the given position and play out the game. (A player may also concede the game before set up.) The winner of the game wins the number of points equal to the other player's bid on his or her own color.

    Using the previous example: If Adam wins the game, he'll be awarded 35 points, the amount Barb bid on black. If Barb wins the game, she'll win 87 points, the amount Adam bid on white. In the event of a draw, each player wins half the amount of the other player's bid. (Adam would gain 17.5 points and Barb would gain 43.5 points.)

  4. The location of pawns and kings is generated by the following process:
    • The program chooses a number at random between two and eight inclusive to determine the number of pawns each side will have. Each side will have the same number of pawns.
    • White pawns are placed on empty squares within the 2nd and 5th ranks inclusive. Location is chosen at random between eligible squares.
    • After the white pawns are placed, black pawns are placed on empty squares within the 3rd and 7th ranks inclusive. Location is chosen at random between eligible squares.
    • After the black pawns are placed, the white king is placed on an empty square that does not put the white king in check. Location is chosen at random between eligible squares.
    • After the white king is placed, the black king is placed on an empty square that does not put the black king in check. Location is chosen at random between eligible squares.

If you want to preserve a position, or show it to someone over e-mail or IM, for example, note that you can cut and paste the URL of a particular game. The board has been "encoded" into a 64-character text string. This is not intended to provide any kind of real security. The hope is that it will hinder players from deducing pawn and king location at a mere glance.

Extra Stuff

How the pieces are generated and placed. Assigning point values to the major and minor pieces (Knight = 6, Bishop = 7, Rook = 10, Queen = 18), the program generates all possible piece-sets worth between 12 and 53 inclusive, and which don't contain more than four of one type of piece. (Note that the 53-point restriction prevents either side from having more than two queens.) The program chooses, at random, one of these piece-sets for the white army. For the black army, the program then chooses, at random, an piece-set with a value no less than the value of the white set, no more than four points greater than the value of the white set, and no more than 53 points.

Once armies have been selected, the pieces are simply placed on empty squares chosen at random.

Rule alterations. Maybe you think Bookie Chess should be spiced up (or down) in some way? Here are some suggestions:

  • First to act determined by coin toss
  • If, after the pawns and kings are revealed, neither player is willing to concede, the stakes double (or increase by some other multiplier agreed upon before the game).
  • Black wins draws
  • Handicaps: if one player is stronger than another, the first player could offer a handicap such that any point gain by the weaker player is increased by some agreed upon percentage. For example, if Carl (weaker player) is getting a 20% handicap from Diane (stronger player), and if Carl goes on to beat Diane after Diane bid 60 on her color, Carl would be awarded 72 points.
Purists, I mock thee. Someone suggested that positions should look more like actual game states. I rejected this idea because I want to reward players who can adapt to unfamiliar formations. Also, I want to reward myself by not having to work on this program any more.

Can I get a witness? Much thanks to Tom Weideman, Aaron Bos, Derek McLain, and Jen Poirier for their help.

Send comments and suggestions! Don't make me beg. Okay, make me beg. Write to:

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