logo (C) Bas Schuiling


STOP is a GO (Weiqi, Baduk) playing program.
It is a go-brain; a program that decides by itself what counter-moves to do for each move the user types in.
Its strength cannot be compared to Google's Alpha Go.

What is Go?

Wikipedia defines Go as: "Go is a strategic board game for two players. It is also known as igo (Japanese), weiqi or wei ch'i (Chinese) or baduk (Korean). Go is noted for being rich in strategic complexity despite its simple rules.".


stop-0.9-005.jar - the usual enhancements, seems to be considerably stronger
stop-0.7-012.jar - more algorithm adjustments
stop-0.6.jar - algorithm adjustments
stop-0.5.jar - Go-fixes (now really no more suicides or KO-moves), GTP fixes, alorithm improvements
stop-0.4.jar - fixed suicide-moves and KO-moves
stop-0.3.jar - implemented the GTP-protocol, added commandline switches
stop-0.2.jar - better freedoms detection
stop-0.1.jar - initial version


To set the board-size, add '--boardsize x' where x is any value bigger than 1.


java -jar stop.jar --mode console
From a GTP GUI:
java -jar stop.jar --mode gtp


Click on: Program -> New Program
Then, for command enter the path to the java-binary with behind it: -jar stop.jar --mode gtp

/usr/bin/java -ea -jar /path/to/stop.jar --mode gtp

What does it look like

In your browser!

You can play against Stop in your current browser by following this link.

Screendump of console-mode

Games played


This is the 4th game played by Stop v0.3 against GnuGO.

Thought process

The movie below shows the thought process of Stop version 0.9-002b. If it does not appear, you can follow this link as well.
BLACK/WHITE are stones placed in an earlier step, GREY: current selected place, blue to green to red: rating for a cross/place, each frame represents a move, only the moves of Stop are shown. In this avi, it plays against GNUGo 3.8-5 on level 1.


Stop plays with several versions at the CGOS server.

Tested with

Verified to run with: