Shade Out

A grid is filled with numbers. Shade out cells until no number appears more than once in any row or column. Two shaded cells may never be horizontally or vertically adjacent, and every unshaded cell must remain connected into a single group.

• Shade cells so each row and column has no repeated number
• Never place two shaded cells next to each other
• Keep all unshaded cells joined in one connected region
• Use these three rules together to find the single solution

• Desktop: click a cell to shade it; click again to mark it safe or clear it
• Phone & tablet: tap a cell to shade, tap again to clear

• Difficulty: easy, medium and hard grids
• Daily puzzle plus an endless practice mode

• A number sandwiched between two equal values must usually stay unshaded
• If shading a cell would isolate a corner, it has to remain unshaded
• Once a cell is shaded, all four neighbours are guaranteed safe

These are Hitori's rules exactly — shade cells until no number repeats in any row or column, never shade two orthogonally adjacent cells, and keep every unshaded cell connected in one group. The puzzle is published by Nikoli, the Japanese house that named and popularised most of this genre.

Hitori means roughly "leave me alone", which is a fair description of the solving experience: the three rules pull against each other constantly.

It is also, formally, a hard problem — Hitori is NP-complete. That is not a curiosity but the reason the puzzles feel the way they do: there is no shortcut procedure, so progress comes from local contradictions rather than from a method you can apply front to back.

Shade Out is the classic cell-shading logic puzzle, rebuilt as an original, solver-verified free browser game with multiple difficulties and a daily challenge.

A free, original browser game on PlayPendium. No download, no install.