M-1098 Kalah Mar61

This memo, dated March 31, 1961, by Roland Silver, describes a "Kalah" game-playing program, likely intended for a PDP computer.

Kalah is a two-player board game played on a board with six "pits" and one "kalah" (scoring hole) for each player. The game begins with three stones in each pit, and both kalahs empty. The objective is to accumulate more stones in your kalah. The game ends when one player's pits are all empty; the opponent then transfers their remaining pit stones into their own kalah, and the player with the most stones in their kalah wins.

Players alternate turns. A move consists of selecting a non-empty pit, removing all its stones, and distributing them one by one, counterclockwise, into subsequent pits – crucially, skipping the opponent's kalah.

Specific rules govern the outcome of a turn:

• Repeat Play: If the last stone lands in the player's own kalah, they get to move again.
• Capture: If the last stone lands in an empty pit on the player's side, and the opposite pit (on the opponent's side) is not empty, the player captures the single stone from their empty pit, plus all stones from the opponent's opposite pit, and places them into their own kalah.
• Game End: If, after a move, all of the player's pits are empty, the game is over.
• Pass Turn: In all other cases, the turn passes to the opponent.

The program interacts with the user via a typewriter for input (selecting moves) and a scope for output (displaying the current board state and other information).