This is the game of Go 囲碁 impleneted in javascript
To run open game.html in browser
The file that contains all the board logic is legal.js. The interesting thing
about it is that it doesn't use a recursive algorithm to score but instead uses
a group data structure to keep track of how many liberties are in each group on
the board. The program then joins two groups when a connecting piece is
placed. This makes it so that the program never has to do more than eight checks
per move to determine if a group should be taken, no matter the size of the group.
The program still can’t join all groups due to some weird fringe cases that are
difficult to check for.