Hints and AI Coach

A hint is always a real technique, found the way the original HoDoKu finds it: the solver tries the techniques from easiest to hardest and reports the first step it finds.

AI Coach walkthrough

Choose Coach me to get progressive Socratic nudges instead of the full answer right away, or click any of the four stage pills on an open hint:

1. Where to look: Tints the house (row, column or box) or endpoints to scan without naming the exact cells or eliminations.
2. The pattern: Names the technique and highlights the key cells, fins or color groups that form it on your board.
3. The logic: Explains why the pattern forces the deduction, drawing any chain links on the board.
4. Conclusion: Shows the final placement or struck-through candidate eliminations.

“Why not?” contradiction prover

Select any empty cell on the board and look at the AI Coach · Ask about rXcY bar in the Hint tab. Click Why not D? for any candidate to test placing that digit in the cell. If the digit is wrong, the AI Coach traces the forced singles that ripple from it until a cell is left with no candidates or a house has nowhere left for a digit, and lets you step through the causal chain on the board. Choose Share proof (or Share step on a hint walkthrough) to copy a direct link that opens that exact board state and proof in the app.

Reading a hint

• The name and a one-line explanation of the technique, with a link to its guide.
• A summary of the step, for example 1 goes in r1c2. Cells are written rXcY: row X, column Y.
• On the board, a legend in the panel explains the colors: key candidates (the pattern), cover candidates, fins, candidates that are removed (red, struck through) and values that are placed (green).
• For chains and loops, lines join the candidates: solid for strong links, dashed for weak links.

Apply step (Enter) places the value or removes the candidates. Dismiss (Esc) hides the hint. Next hint asks for another step from the current position.

Hints use

This setting limits how hard a hint may be: Singles only, Up to Easy, Medium, Hard, Unfair, or Everything. A puzzle that needs more than the limit allows gets the answer that no such step exists, which is a useful result in itself.

Individual techniques can be switched off as well, under Settings → Techniques a hint may use. The level is the upper cap; unticking a technique narrows it further, so a hint never uses a technique you would rather spot yourself. With every technique ticked (the default) nothing changes.

All steps

The All steps tab lists every step available right now, grouped by technique with counts. Select the steps you want and choose Apply selected, or Refresh after you have changed the board. The Path tab goes further and walks the solver's whole route from here (see Solution path).