Chess pool - ver. 0.50

For two players

by Robert Price

Chess pool is played on a pool table with standard pool equipment, beginning with a rack of nine balls as follows, viewed from the front (the 1-ball faces the breaking player)

The player who breaks chooses, after the break, whether to control solids or stripes (solids being the balls ("pieces") numbered 1-4 and stripes, 9-12).

Players alternate, taking only one shot per turn. On every shot, the player strikes the cueball which must strike a friendly piece, and must not first collide with an opposing piece or the 8-ball -- unless the player has no friendly pieces remaining, in which case the cueball must strike the 8-ball before any other. Violation of any of these conditions incurs a foul. If the cueball ever lands in a pocket, the shooter has scratched.

Whenever the 8-ball is pocketed or captured, except in case of a foul or scratch, the shooter puts it back into play in place of an opponent's piece, which is removed from the game. If the shooter's opponent has no pieces remaining, then the shooter has won the game.

Balls pocketed on the break remain pocketed except in case of a scratch; and the 8-ball is replaced as usual after the breaker chooses which pieces to control. Regardless of whether pieces were pocketed, the second player has the first shot after the break.

The Turn

On a turn, if there are at least two object balls on the table, the player chooses to SLOP or MOVE:

Slop

The player shoots and, except in case of a foul or scratch, all balls thus pocketed are removed from the game. If the 8-ball is among them, it is replaced; see above.

Move

This option is a good deal more complicated, and requires the introduction of the names for the pieces:

  1, 9 (Yellow)  - Rook
  2, 10 (Blue)   - Knight
  3, 11 (Red)    - Bishop
  4, 12 (Violet) - Queen
  8 (Black)      - King

Also note that the pool table is divided into an 8x4 grid of spaces by the three spots on each short edge and seven on each long. This grid is regarded as half a chessboard.

The shooter names a friendly capturer and a target, which can be an enemy piece or the 8-ball. The target must lie in a space to which the capturer could legally move in Chess (ignoring the restrictions about putting one's King in check and jumping over intervening pieces). The shooter may name the King as a capturer if and only if there are no frindly pieces remaining on the table. After making the call, the shooter shoots.

If the cueball hits another ball before the capturer, or if the capturer then hits another piece before the target, the shot is considered a slop. Otherwise, for every collision between opposing pieces, the piece that was at rest is "captured" (If both were in motion, both are "captured").

Note the following clarifications:

A ball is considered at rest until it participates in a collision. Then it is considered to be in motion until the end of the shot, even if it stops rolling before that time.
"captured" pieces can still cause others to become "captured" - thus, for example, the target can take the capturer to the grave with it.
The King is considered to be the shooter's piece if it was named as the capturer. It is considered to be an opponent's piece if it was named as the target. Otherwise, it is neither, and so cannot become "captured", nor cause another piece to become "captured". This resistance to capture is called the 'diplomatic immunity' of the king.
Note that the King can be named capturer only if the shooter has no other piece left on the table, but that it can be the target no matter how many pieces the opponent has.

At the end of the move, all "captured" pieces are removed from the table, along with any pieces that landed in a pocket. If the shooter fouled or scratched, its opponent places all pieces removed on the shot. If the 8-ball was legally removed, it is replaced; see above.

Endgame

If all pieces except the 8-ball have been removed from play, the shooter wins if s/he pockets the ball, but loses immediately if s/he scratches.

Scratching

If the cueball lands in a pocket, the shooter's opponent places it and the 8-ball before shooting, as well as any object balls pocketed on the scratch. The moral of the story: Don't scratch.

Fouling

If a shooter's cueball fails to hit a friendly piece (or 8-ball in the absence of friendly pieces) before any other, or if no ball strikes a rail or lands in a pocket, a foul is called. The fouler's opponent places the cueball anywhere on the table before shooting, as well as any pieces pocketed on the foul.