Go (Baduk)
Play the computer and watch the estimated score move with every stone
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About this tool
Place stones on the line intersections and surround more territory than your opponent. Choose a 9x9, 13x13 or 19x19 board and play the computer, two players on one screen, or a friend over an invite link. After every move the position is re-evaluated and shown as an estimated win rate and point difference. Playing alone, the board and every calculation stay inside your browser and nothing is sent to a server. Only when you play over a link do your moves pass through the server - it has to reject illegal ones. Even then the territory estimate and win rate are still computed only in each browser.
How to use
- New to Go? Start on 9x9 - a 19x19 game can take over an hour.
- Tap an empty intersection to place a stone. The latest move is marked with a red dot.
- Surround an enemy group completely and it is removed from the board (a capture).
- Nothing worth playing? Press Pass. Two passes in a row end the game and count the score.
- Turn on Show territory to see which way each empty point currently leans.
- Undo takes a move back. Against the computer it takes back both moves; against a person your opponent has to allow it.
Frequently asked questions
- How is the win rate calculated?
- Not by a neural network. AlphaGo-style engines (KataGo, Leela) need tens to hundreds of megabytes plus an inference on every move, which is not workable in a web page. Instead this uses a long-established influence calculation (Bouzy dilation/erosion) to estimate who each empty point belongs to, then converts that point difference into a percentage. That is why the point difference is always shown next to it - the estimate follows the opening and middle game reasonably but cannot read life-and-death.
- Why can I not play here?
- One of three reasons: a stone is already there, the stone would have no liberties the moment you place it (suicide), or you are trying to immediately retake a stone that was just captured (ko). The board tells you which one in a single line.
- Which scoring rules are used?
- Chinese area scoring: your territory plus your living stones on the board. There is no agreement phase for dead stones, so anything capturable must actually be captured to count. Komi is 6.5.
- How strong is the computer?
- Beginner level. It captures when it can, runs when it is about to be captured, and heads for the corners and sides in the opening. It does not read deeply, so it collapses under a sharp attack. It runs inside your browser, so the position is never sent anywhere.
- Can I play a friend over a link?
- Yes. Press the co-play button to create a room; whoever opens the link becomes your opponent, and anyone after that watches. The board size is fixed when the room is created so both players always see the same board. An undo takes back one move only, and only if your opponent allows it.
- Can I choose the computer's difficulty?
- Yes. Pick from Easy, Normal, or Hard. Even on Hard it does not read many moves ahead - in a tough position it just widens its search to more candidate moves and re-evaluates the position, rather than looking deeper.
- Can I resign in a room game?
- Only whoever is seated and playing sees a Resign button, and it asks for confirmation before ending the game. A resigned game is recorded as a resignation rather than a score, so an unfinished board's territory count never gets shown as if it decided the win.