Hexodic

Hexodic move-legality checker.

Build a position, propose a turn, and let the rules engine rule on it step by step.

Get it on the App Store All rules tools

Move-legality checker

This tool runs the game's rules engine on this page and needs JavaScript. Everything it computes is described in the text below.

Empty = the starting position. Each number picks one turn from the engine's list of legal turns.

Project
Shape
Echo

The Hexodic move-legality checker answers that question by comparing your proposed turn with the rules engine’s own list of legal actions, one step at a time: first the Project, then the Shape that follows it, then the Echo. A Hexodic turn is legal only when all three steps are legal in order, because each step changes what the next step may do.

How to use the checker

  1. Set the position. Leave the replay code empty for the opening position, or paste a replay code from the branching-factor explorer. A replay code is a dot-separated list of turn numbers taken from the engine’s ordered list of legal turns.
  2. Describe the turn. Choose Place or Move with its cells, a Shape (raise, lower or skip) with its cell, and an Echo choice. Selecting a board cell fills in the destination.
  3. Check it. The checker reports each step as legal or illegal, with how many options the engine allows at that step.
  4. Continue. When a turn is legal you can play it, and the position advances so you can check the next turn.

What the checker computes

  • Staged legality from the engine’s legal Project, Shape and Echo lists, confirmed by the engine’s whole-turn legality check.
  • Capture flag for moves — whether a move captures the stone it lands on is decided by the engine, not by you.
  • Result of a legal turn — the cells captured and, if the turn ends the game, the win condition: Network, Takeover or Strangle.
  • Position summary — reserve, Echo charges, captures and whether each player’s Network or Takeover condition is complete, as reported by the engine’s win checks.

What the checker cannot determine

The Hexodic move-legality checker does not explain why an illegal step is illegal beyond reporting that the engine does not list it. The checker cannot see a game’s history, so a repetition loss is never reported. The checker also does not judge whether a legal turn is a good turn.

Learn the turn structure in how Hexodic is played, or read about deterministic strategy games. Then get the Hexodic app.

Reviewed 2026-09-15.