DIAMONDS & PIVOTS 

Copyright (c) 2005 João Pedro Neto

This game is played on the following hexagonal board.

 

DIAMOND - A pattern of four connected friendly stones arranged in two connected lines of two stones each. TURN - Each players passes or drops a friendly stone over an empty cell. If any diamond patterns with four friendly stones are made, the player must choose one, choose a stone from it (the pivot), and place its other three stones in a line starting from the pivot. Every stone (of either color) that was on those destination cells are captured and removed from the board. If, after a pivot movement, another diamond is made, the player must repeat this procedure. PIE RULE - After the first drop, the second player may swap sides. GOAL - After two passes, wins the player with more stones (if the number is equal, wins the second player)

 

An example Black's turn. He dropped the marked stone, making a pivot (the four top black stones).           Then, he chooses c5 as the pivot and make a line in such a way to create two new diamonds. Black must now select one of them and continue moving.           Black picks the lower diamond, uses f5 as the pivot and uses the remaining three stones is a way to capture 2 white stones. White's position is weaker than Black's, however he may try to reply by dropping at [1] which guarantees a diamond in the next turn.

Some notes from Bill Taylor:

First I note that the tactic of tank-like crawling is unstoppable:

x x x x . . .       . . x x . . .       . . . x x x x
 x # . . . . ---->   . x x x x . ---->   . . . x x .   ----> etc

Now this is not necessarily a bad thing, though it may become a little
predictable, perhaps.  Nonetheless, it can be accounted for.
At first I thought the board was too small, and would need expanding,
but in fact we can *just* get it onto our board.  It appears to show
that the worst opening move is NOT in the corner, but on the side!

    . . . , .  
   . . . , . .      Black's opening move here can be worked up into 
  . . . , . . .     a "tank" going along one of the two comma lines,
 . . . , . o . .    which means that the o move can be as shown,
. . . , . . . . .   or even slightly closer to the comma tracks.
 . , , , , , , ,  
  x , . . . . .     I think we could keep this in mind now.
   . . . . . .      I think the opening advantage is still very great,
    . . . . .       and the opener needs to go to this worst spot,
                    to get the best out of the inevitable(?) swap.