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Search depth (plies): 6

What the machine values:

Depth is how many plies the machine looks ahead: a ply is one move by one side, so depth 2 means its move and your reply. The evaluation is not a probability — it is a score in points from the computer's point of view: a man is worth 100, a king 300, and the rest is positional seasoning. Plus favours the machine, minus favours you.

Draughts against the computer

Play Russian draughts (checkers) online against the computer: captures are mandatory and kings fly across the board. Free, no sign-up, in the browser.

What this game is

Russian draughts is a game about the forced move. Capturing is compulsory, which turns every offered piece into an order: your opponent has to take it, even when taking it wrecks his whole position.

That shapes the play. Games are rarely won by slowly piling up an advantage; far more often a four or five move combination decides everything, one where you give up a piece or two to collect three. And then the second half begins, with kings that fly across the board and capture from any distance.

Rules

How to play better

A bit of history

Draughts did not grow out of chess but out of a much older game, alquerque, which reached Spain with the Arabs and is documented as far back as the tenth century. Medieval Europe moved it onto a chessboard, and what came out is what we call draughts. The flying king arrived later, following the chess reform of the late fifteenth century that gave the queen and the bishop their long range.

Since then the game has split into dozens of variants, and the differences are fundamental. Russian draughts uses an 8×8 board, a flying king, and men that capture backwards. The international game is played on 10×10 with 20 pieces a side. English draughts, also called checkers, is 8×8 as well, but there a king moves a single square and a man captures forwards only.

It was English draughts that was solved outright in 2007. Jonathan Schaeffer's group at the University of Alberta, who had worked on the Chinook program for nearly two decades, published the proof in Science: with perfect play from both sides the game is a draw. Russian draughts, with its flying king, is orders of magnitude larger and remains unsolved.

This version follows the applet that ran on this site from 2005 and implements the Russian rules in full: crowning in mid-capture, the Turkish strike, the draw after 15 quiet king moves. There is no majority rule here — of several available capture sequences you may take any, as long as you play it out.

About the levels

Easy looks exactly two plies ahead — its move and your reply — and judges the result by material alone: a man is worth a hundred, a king three hundred. It sees neither advancement nor the centre, gives itself no thinking time and answers instantly.

Hard searches with iterative deepening down to six plies, inside about four tenths of a second. On top of material it counts how far a man has advanced towards promotion and adds a small bonus for the sixteen central squares — so it already understands that a man near the crowning row is worth more.

Expert goes as deep as twelve plies and spends around seven tenths of a second per move. Its real advantage is quiescence: a position with a capture still pending is never evaluated, the search is extended until the capture sequence is over. That is why it cannot be caught by a combination beginning just beyond the horizon. It also values king mobility, and in the endgame, once eight pieces or fewer are left, the stronger side stops shuffling and drives its kings straight at the enemy.

Where to go from here