English is the default. Your choice applies to all games and lessons.
The new game starts empty with Black to move. Your study and diagram remain separate.
+0.5 is an experimental tie-break, not established balance.
Place on an empty point. Connected stones of one color share their distinct empty neighbors: their liberties. Remove every opposing chain with no liberties, then reject suicide. A move may not repeat any earlier complete board coloring.
Passes leave that history unchanged. Two consecutive passes finish immediately. Count each own stone and each empty point in a region touching only that color; add White's fixed komi. Regions touching both colors or neither are neutral.
No automatic dead-stone removal: play out disputed groups before passing twice. Winding chains have no special immunity. A large drawn face is not an extra empty point.
The default +0.5 komi is experimental. These are area rules with no suicide and positional superko, not Japanese or exact Tromp–Taylor rules.
The marked connections show actual neighbors. Möbius has one physical boundary; Klein and genus two have none. Each point appears once, even when its neighbors are in another chart.
Click an empty point to place a stone. Click a stone to inspect its entire chain and highlighted liberties. Arrow keys follow actual adjacency; Enter or Space activates the focused point. Page Up and Page Down switch charts. Rotate changes the view. Escape clears inspection.
Ctrl/Command Z steps back; Shift adds redo. A move from an earlier position branches from that exact prefix and keeps its repetition history. Play and Study are separate. Editor diagrams begin a new study with unknown earlier history, clearly labelled.
Use Save to keep a game, study or unfinished diagram as JSON. Invalid browser autosaves are preserved for recovery and never automatically overwritten.
JavaScript is required to play Go and edit diagrams.
Crab Canon