ZRTZ 

Copyright (c) 2000 Kris Burm

Zrtz is played on the following initially empty hexagonal board.
There are initially offboard 6 white stones, 8 gray stones and 10 black stones. 
All stones belong to both players, except those that are captured.


  • MOVE - On each turn, each player must do one of the following things:
    • Place one of the available offboard stones on an empty cell, and then remove an empty cell at the board edge (herein, I will place a marker in the sample diagrams) such that the player must be able to remove it from the sides without disturbing the position of the remaining board cells..
      • ISOLATION - If, after a board cell removal, the board is disconnected into two sets of cells this is valid - if and only if - at least one of those clusters does not have empty cells (i.e., all cells are occupied by stones). Those cells are removed from board, and those stones are captured by the player who made the move. This is the only capture that is not mandatory.
      • If there are no more stones offboard, each player must use their own captured stones and drop them again onboard. 
      • If, after a drop, all cells are occupied, wins the player that made that move (because there is a cluster with no more empty cells, which makes this an isolation capture).
    • Capture one or more stones by jumping.
      • Capture is compulsory and has precedence of the first moving option.
      • Capture is done like in Checkers, jump over an adjacent stone (of any color) and land on the immediate empty cell.
      • Capture is multiple, after the first capture, the player must continue if more captures are available. There is no restriction to make the maximum capture.
  • GOAL - Wins the player that first captures 3 white stones, or 4 gray stones, or 5 black stones, or 2 stones of each color (i.e., 2 white, 2 gray and 2 black).

There is a tournament rule that restricts the winning condition to 4 white, 5 gray, 6 black or 3 stones of each color.

A capturing example

If a player drops the marked white stone and removes cell [1], the other player will be forced to capture it with the black stone, and then the first player will capture it with the gray stone landing on cell [2].

Isolation capture

After the drop, if a player removes cell [1] he will capture the marked black stone.

More information can be found at the GIPF project website - Zrtz it's the 3rd game of a series of 6. There is also a remarkable strategy guide. There's also a diagram tool to handle Zrtz positions, called ZF1, created by Michael Reitz. You can play Zrtz at Rognlie's PbM server.

One variant, by Bill Taylor at 2002, called RUST uses the same concept but with one type of stone for each player:

A player may jump over any piece, an enemy piece is captured, a friendly piece returns to playing stock, otherwise Zrtz mechanics and rules. Capture is mandatory over dropping. If a player cannot move he must pass. When both players pass, the game ends. Wins the one with more captured stones.

Here is a sample game (sorry, no format...) ':' means an enemy capture, '.' means a friendly capture.

INITIAL POSITION

     abcdefghijklmnopq  
1.      . . . . .      
2.     . . . . . .    
3.    . . . . . . .    
4.   . . . . . . . .  
5.  . . . . . . . . .  
6.   . . . . . . . .  
7.    . . . . . . .    
8.     . . . . . .    
9.      . . . . .

     xxx     ooo             xxx     ooo          xxx      ooo
1. g3 I9   f2 E1       11. o7 B4   m9 G1 21. k1 M5    l4.j2
2. h4 H8?  h6 G7       12. p6.m8   m9:o7 22. k1:i3    k3 J4
3. g3.i5   h6:j4       13. m1 C5   p4 K5 23. i3:m3    n2:l4
4. g1 H6   h4 J6       14. m1:o3   p4:n2 24. resigns  8-9
5. g1:e3   j4.f4:d2    15. j4 B6:  j2 I1
6. o3 F2   a5 L6       16. i5.k3   j2:l4
7. i5 E3   m5 C3.      17. m5 N6   j2 F4
8. k5 G5?  n6 M7       18. m5:k3   j2:l4
9. k5:o5   n6:p4:n2    19. i7 J8.  k9 M9.
10. p6 K7   q5 L8       20. n8 P6:. k3 M1

FINAL POSITION

      abcdefghijklmnopq  
1.             .        
2.          . . . .    
3.         . . . . .    
4.          . . o . .  
5.           .     . o  
6.
7.
8.
9.