Kalah rules

Six pits a side, four seeds in each, a store at each end. On your turn, pick up all the seeds in one of your pits. Sow them one at a time counter-clockwise: through your own pits, into your store, then along the opponent's pits. Never sow into the opponent's store.

Last seed in your store: take another turn. Last seed in an empty pit on your side, with seeds opposite: capture the opposite pit and your last seed into your store.

The game ends when one row is empty. The other player moves all seeds still on their side into their store. The larger store wins.

Boards come with three, four, five or six seeds in each pit. The notation Kalah(6,4) means six pits and four seeds. More seeds make a longer and harder game. Four is the usual choice, and the one this site plays by default.

In the standard game you capture only when the opposite pit holds seeds. In the empty-capture variant you also capture your single last seed when the opposite pit is empty. Many computer programs and apps use empty capture without saying so. The rule builder has a switch for it.

Clockwise sowing makes it harder to reach your store. "Seed on" removes captures. When the last seed lands in an occupied pit you pick it up and keep sowing. The turn ends only in an empty pit. Some families give the remaining seeds to the player who emptied their row, or do not count them at all. Some let seeds drop into the opponent’s store as well. Tournament play adds the pie rule. After the first turn, the second player may take over the first player’s position. That makes the strong opening moves a risk. All of these are switches in the rule builder.

Kalah has been solved by computer. Under standard rules, Kalah(6,4) is a win by 8 seeds for the first player with perfect play. Kalah(6,5) is a win by 10. Kalah(6,6) is at least a win by 4 (Mark Rawlings, 2015). Under empty-capture rules, Kalah(6,4) is a win by 10 and Kalah(6,5) a win by 12 (Geoffrey Irving and Jeroen Donkers, 2000). Kalah(6,6) is a win by 2 (Rawlings, 2015).

This is why some sites use the pie rule: the first player moves, then the second player may choose to swap sides. The strategy page shows what each first move is worth.