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Rotary. On a 9 by 9 board with rotating pieces. (9x9, Cells: 81) [All Comments] [Add Comment or Rating]
twixter wrote on Sun, Nov 11, 2007 07:04 PM UTC:
Rotary is based on Ploy, and constitutes an improvement over that game IMO.
I suspect that computers may solve Ploy some day, finding a specific
opening repertoire with smashing attacks. I believe Ploy is more
imbalanced than chess, although it hardly matters for casual play. Rotary
is much deeper and better balanced, and involves long-range planning and
strategical concepts which chess players can latch onto.

If you have a Ploy set and an extra set of pieces, you can add Rotary to
your box. You could grind down the direction pointers on 18 pieces to make
the pawns, and add a circular disk on the back to indicate a promoted pawn.
A photo of such a set is at

One nice feature of Rotary is that draws cannot happen due to insufficient
material. If just the two kings remain on the board, one will always be
able to force checkmate on the other! It's an interesting puzzle to solve
this 2-piece endgame. My solution, presented without proof, is at scroll down a bit for the

Here are the rules for this 2-piece endgame: The board is a square 9x9
grid. Each king is a circular disc with pointers in four directions, which
looks like an X or like a + depending on how it is oriented. A move
consists of either rotating without moving, or moving one space in an
indicated direction followed by optionally rotating. The only way to
rotate is to change from X to + or vice versa. You may not pass.