Baduk Han Su
Web Go against KataGo, the open-source Go AI. Pick an opponent anywhere from 18 kyu to 9 dan and play on a 9×9, 13×13 or 19×19 board. Nothing to install, no account.
What it is
Baduk Han Su is a game of Go played against an AI instead of a person. Open the address in a browser and the game starts — there is nothing to download and no account to create.
The opponent is KataGo, the open-source Go AI released after AlphaGo. On top of superhuman playing strength it was trained to predict the score, so it can tell you not just who is winning but by how many points.
The part that matters most is that you choose how strong the opponent is. AI Go engines are usually far too strong to learn anything from; here you pick a level anywhere from 18 kyu to 9 dan.
Who it is for
- Beginners who know the rules but have nobody to play
- Players who want quiet practice games before facing a person
- Anyone who wants a light 9×9 game on the commute
- Dan players who want an opponent worth a real fight
Choosing a board
A 9×9 game is over in ten minutes and the stones collide immediately. It is the best board for practising life and death, and the one to start on.
19×19 is the full board — you play through the opening, the middle game and the endgame as one arc. 13×13 sits in between, a stepping stone when 19×19 still feels vast.
You also choose your colour. Black plays first; White takes komi in exchange.
Ending a game
When there is nothing left worth playing, pass twice in a row or tap Score. The territory is counted and the winner decided. Scoring is done on the server with KataGo, so the points that beginners find hardest to judge are settled for you.
You can also resign at any time. A resigned game is recorded as a win by resignation, with no score counted.