Surakarta

Permainan Surakarta · the Javanese loop-capture game

Red to move

12 Red12 Black

0You

0Computer

0Draws

Opponent

Show pieces that can capture Warn me when a piece is under attack Show coordinates

Rules

Each player has 12 pieces on the two rows nearest them. Pieces stand on the points where lines cross. Players agree who moves first, then turns alternate.
Moving: move one piece a single step in any direction — forwards, backwards, sideways or diagonally — to an empty point.
Capturing: travel along a circuit — the inner or the outer — through at least one corner loop, and land on an enemy piece to capture it.
The journey may cross any number of empty points before and after the loops, even the same point twice, and the piece's own starting point counts as empty. It can never jump over a piece.
The loops are only used for capturing. Capturing is never compulsory.
Forward only (a popular house rule against slow, shuffling openings): an ordinary step must go to one of the three points towards the opponent — straight or diagonally forward. Captures may still go any way round. A side left with no move at all ends the game, and the pieces are counted.
Winning: capture all 12 enemy pieces. If neither side can make headway, the players agree to end the game (Count) and the side with more pieces wins. After 40 moves each without a capture the game is counted automatically.
Matches: each game scores the pieces you still have in play. Play a fixed 4 games (the first move alternates) or race to 30 points; the higher total wins.

Tips for beginners

Control the centre. The middle points sit on both circuits, so a piece there can strike round several loops in different directions.
Stay out of the corners. No circuit runs through the four corner points: a piece there can't capture, can barely move, and is easily shut in.
Watch the lines, not the distance. A piece far away can strike in one move if an open line connects it to you through a loop. Scan the board before every move.
Open lines to attack, block them to defend. Move your own pieces off a line to clear a long-range route; leave one standing on a line to shield the pieces behind it.
Guard your pieces. A piece is safe to leave in reach only if one of yours can capture straight back on that point.
Set traps. Aim your loops at the empty points next to enemy pieces, so any step there is captured.
The first capture matters. Once a side is a piece up, the other must defend more lines with fewer pieces. But capturing is optional — don't take if the enemy takes straight back.
If games stall with both sides shuffling, try the Forward only rule.

How the computer plays

Routes. For every piece it traces both circuits in both directions to find every capture a loop makes possible, and which empty points each piece sweeps.
Look-ahead. It searches several turns deep with alpha-beta search, trying captures first. At the end of each line it plays out the captures still available, so it takes only when the exchange pays — capturing is optional, and it will wait.
Centre, not corners. It prefers points in the middle, where a piece reaches both circuits in several directions, and keeps out of the four corners, where a piece can never capture.
Protected paths. A piece the enemy can reach round a loop counts against it, much more if no piece of its own guards that point to take back. It shuts open lines by standing on them.
Traps. It values empty points its loops sweep next to your pieces: step there and it captures.
No shuffling. It remembers positions it has already made and avoids going back to them unless it is losing.
Levels. Easy looks one move ahead and often misjudges. Medium thinks for under a second, Hard for up to three.