Pit of Pillars is an elimination game. There are two players, Red and White. Each has a sufficient number of men and a sufficient number of pillars at his disposal. The board is 8x8 with the cornersquares omitted.

PoP position

Definitions
  • The "capacity" of a square equals the number of its orthogonal neighbors. The board initially has 8 c2 squares, 16 c3 squares and 36 c4 squares.
  • Men move in "stacks". A single man is a stack of one. Stack s may have any composition and are controlled by the color on top.
  • A "pillar" is a piece that, if it occupies a square, reduces the capacity of the squares next to it by one.

Rules
There are two stages, the entering- and the movement stage.

The entering stage
The game starts with the board empty. White starts by entering one man. From that point on players take turns to:

  • enter a man next to the man just entered by the opponent, and ...
  • ... enter a man so that it has only vacant squares next to it.

Both placements are compulsory. When the player to move can no longer enter the second man, then his turn ends and his opponent may start the movement stage. The number of white and red men will always be equal, although the 'density' of the position may vary and either player may end up being the one to start the next phase, depending on whether the number of full turns was even or odd.

The movement stage
On his turn a player must either move one of his stacks or enter a man from his stock of reserves.

  • A stack moves horizontally or vertically, based on the number of men to be moved (e.g. one man moves 1 square and a stack of three moves 3 squares). Stacks may be split in the process: a player may choose for instance to move only the top man (1 square) or the top two men (2 squares) of a larger stack. Stacks may move over or onto any square, whether vacant or occupied, but they may not move over or onto a pillar.
  • Instead of moving a stack, a player may choose to enter a man on any vacant square or on any stack.
  • After this compulsory part, a player may move one of his pillars. Pillars move like queens in chess, but cannot move onto or over stacks or pillars.

Capture
  • If moving or entering causes a bi-colored stack to surpass the capacity of its square (or to be heightened, if it is already on or above capacity), then the moving player's men in it return to his stock of reserves, while the opponent's men are removed from the game. At the same time a pillar of the capturing player's color is put on the square.
  • The emergence or movement of a pillar may cause a stack on an adjacent square to reach or surpass capacity. There is no 'cascading effect': such a stack simply remains on or above capacity and may (or may not) be captured by the opponent on his next turn.


Object
A player wins by leaving the opponent without any stacks on the board, regardless of how many reserves remain in either stock, or whether his own last stack has disappeared from the board in the process. A player may and will get into positions he'd rather avoid, where he has ample reserves but cannot capture for lack of pieces on the board! Draws are only possible by cooperative cycles and thus excluded in regular play.