Go
Play Go on a 9×9 board against a rule-based AI opponent. Simple rules, deep strategy — no sign-up required.
How to Play Go
- Black moves first. Click any empty intersection to place your stone.
- Surround an opponent's group of stones on all sides to capture it — captured stones are removed from the board.
- Surround empty intersections to claim territory. The player who controls more territory and captures wins.
- Click Pass if you have no useful move; two consecutive passes end the game and trigger scoring.
Frequently Asked Questions
- What board size is used?
- The game uses a 9×9 board — the ideal size for learning Go without the length of a full 19×19 game.
- What is a liberty?
- A liberty is any empty intersection directly adjacent (not diagonal) to a stone or group. A group with no liberties is captured and removed.
- What is the ko rule?
- Ko prevents an immediately repeated board position. If capturing a stone would recreate the previous position, that capture is illegal until another move is made elsewhere.
- What CPU strategies are available?
- Two. Best follows the rule-based priority order and always takes the highest-scoring point for the rule that fires. Random plays any legal point with no rules or scoring — a useful baseline to play against while you learn.
- How does the rule-based AI choose a point?
- It works down a priority list: capture a group outright, save one of its own groups that is down to its last liberty, connect a group that is running short of liberties, put an enemy group in atari, then take territory — preferring points that leave its own new group with three or more liberties. Corners come before the centre, and the centre before the edge.
- Why does the AI pass?
- When no move on the board matches anything above the fallback rule, the AI has judged that every remaining point costs more than it gains, so it passes rather than filling in its own territory. Two consecutive passes end the game and trigger scoring.