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Colorful Osmosis Chess

Colorful Osmosis Chess uses four basic piece types (plus Kings and Pawns). Two basic pieces are colorbound and two are colorswitching. Of the colorbound pieces, one is a slider and the other is a leaper; likewise for the colorswitching pieces. Basic pieces can create compond pieces by capturing enemy pieces, in some games this process is called absorbtion, here I use the synonym osmosis. Colorful Osmosis Chess is played on a ten-by-ten board.



White's  pieces are set up  as follows: Camels on the corners. From left to right on the second rank are Harvestman, Knight,  Bishop, Guard, King, Bishop, Knight, and Harvestman. On the third rank are ten Pawns, Black's army is placed in mirror symmetric positions  on the eighth, ninth, and tenth ranks.


Basic Pieces

Compound Pieces


The usual FIDE checkmate, stalemate, triple repetition and fifty-move rules apply. In addition, promotion is not limited to Pawns.Basic pieces may promote as follows:

  1. Capturing a Pawn, Guard, or the corresponding basic piece does not cause promotion.
  2. Capturing any other basic piece resuls in promotion to the compund piece with the combined move of captor and captive.
  3. Capturing a compound piece which shares the captor's move results in promotion to the piece captured (in essence the captive swiches sides).
  4. Capturing a compound piece which does not share the captor's move results in promotion to a compound piece combing the captor's move with one of but not both of the captive's basic moves. (Capturing player chooses.)

This process of promotion by capture is called osmosis.

All Possible Promotions
Captured Piece Captured by Bishop Captured by Knight Captured by Camel Captured by Harvestman
Bishop --- Cardinal Caliph Evangelist
Knight Cardinal --- Gnu Battlemaster
Camel Caliph Gnu --- Imam
Harvestman Evangelist Battlemaster Imam ---
Cardinal Cardinal Cardinal Caliph or Gnu Evangelist or Battlemaster
Caliph Caliph Cardinal or Gnu Gnu Evengelist or Imam
Evangelist Evangelist Cardinal or Battlemaster Caliph or Imam Evangelist
Gnu Cardinal or Caliph Gnu Gnu Battlemaster or Imam
Battlemaster Cardinal or Evangelist Battlemaster Caliph or Imam Battlemaster
Iman Caliph or Evangelist Gnu or Battlemaster Imam Imam



Colorful Osmosis Chess began as an effort to use both colorbound and colorswiching sliders and leapers. Three of them are Bishop, Knight, and Camel. For the fourth basic piece I used Jörg Knappen's Harvestman from his Seenschach.  The osmosis rules are adapted from the assimilation rules of Fergus Duniho's Assimilation Chess with the following changes:

The abscence of castling, Pawn promotion before the last rank, and especially the promotion of non-Pawn pieces is reminiscent of Shogi. Osmosis (promotion by captute) is found in several large Shogi variants such as Maka Dai Dai Shogi as well as Assimilation Chess.


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By Michael Nelson.

Last revised by Ben Reiniger.

Web page created: 2023-10-27. Web page last updated: 2024-01-21