Crab Canon
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TimeGo

One board. A past you can change.

Detailed TimeGo rules and replay explanations are currently in English.

Black to move

5 × 5 · zero komi

Choose an empty point to place a stone.

Current board

Rings mark movable births in Time mode. Small squares mark locked births.

Current placement order

This order can change. The turn record keeps every action.

    Save TimeGo game

    The entire turn record and viewed position are saved. Loading reconstructs the mutable history, locked boundary and both repetition records.

    TimeGo rules

    Black starts. Each turn, place a stone, move an eligible stone’s birth earlier, Lock the shared past, or pass. Adjacent stones form groups; empty adjacent points are liberties. Capture opposing groups with no liberties, then reject suicide.

    To travel, choose your own live stone born after the locked boundary. Keep its intersection and move its placement before an earlier unlocked placement. Arrival must be legal. Replay the remaining placements in order; permanently cancel any that now occupy a stone, self-capture, or repeat an earlier board. The traveler can die during replay. The reconstructed colors need not alternate; actual turns always do.

    Lock spends a full turn and fixes all current placements for both players. It cannot be used when the whole history is already locked. Later stones may still travel within the new unlocked suffix. Locked stones can still be captured.

    Two separate repetition rules apply: no board coloring repeats within the reconstructed placement history, including the empty board and locked prefix; no non-pass action may restore a placement history and locked boundary already visited in actual play. Passes and Lock never erase repetition records.

    Two consecutive ordinary passes end the game. Count actual stones plus empty regions touching only one color. There is no prisoner score or presumed-dead removal. Zero komi is provisional; equal area draws. A time move may change only the history and leave the present board unchanged.

    Complete rules and records

    Board and keyboard help

    Place mode: select an empty point to play. Time mode: choose your own ringed stone to see a possible present. Slide its birth backward, choose a nearby placement, or use the exact arrival menu. Explore freely: only Play time move spends your turn. Watch replay animates the consequences; Compare shows original and rewritten boards. Inspect mode shows a group’s liberties. A1 is at bottom left.

    Arrow keys move focus; Enter or Space selects. Home and End focus the first and last intersection. After choosing a traveler, arrow keys on the arrival slider move its birth through the past. Replay has its own step slider and play/pause control. Escape cancels a time preview or closes a menu. Ctrl/Command Z reviews the previous turn; add Shift to move forward. Review preserves the future until you confirm a new branch.

    The placement order is the editable past. The turn record is the actual sequence of actions, including time moves, Lock and passes. Save exports the full line even while reviewing. The tutorial exercises are separate from your game.

    Autosaving uses a dedicated TimeGo record and protects against conflicting tabs. Export before leaving if saving is unavailable. Unreadable saves remain downloadable from Menu. Application limits never score or silently truncate a game.