How to Play Mosaic

The Board

Each Mosaic puzzle is played on a grid — the daily standard puzzle uses a 9×9 grid; the easy mode uses 5×5. Every cell is either black or white. Some cells display a number clue. Your goal is to determine the color of every cell so that all clues are satisfied at once.

Unlike Minesweeper, the entire constraint system is visible from the start. You never click to reveal anything — you simply decide: is this cell black or white?

Reading the Clues

Each number on the board tells you the exact count of black cells in the 3×3 neighborhood centered on that cell — including the cell itself. A cell always counts itself as one of its own neighbors.

• A corner cell has a 2×2 neighborhood (4 cells, max clue = 4).
• An edge cell has a 2×3 neighborhood (6 cells, max clue = 6).
• An interior cell has the full 3×3 neighborhood (9 cells, max clue = 9).

This is the same counting logic as Minesweeper's mine-count numbers — if you can read a Minesweeper board, you already understand Mosaic clues.

Controls

Every cell without a clue starts in an unknown state and cycles through three states:

• White (empty) — you have marked this cell as not black.
• Black (filled) — you have marked this cell as black.
• Unknown — not yet determined; the starting state.

Left-click advances: white → black → unknown.
Right-click advances: black → white → unknown.

Clue cells change color as you fill their neighborhood: a green clue means exactly the right number of cells are black — that constraint is fully satisfied. A red clue means too many cells in its neighborhood are black — undo one.

Win Condition

You win when every numbered clue is green simultaneously. There is exactly one configuration of black and white cells that achieves this — every puzzle is computer-verified to have a unique solution reachable by pure logic.

Basic Patterns

These patterns let you fill or clear entire neighborhoods in one move. Always scan for them first — they require no reasoning beyond recognising the clue value.

Clue = 0 — clear all neighbors

Zero black cells anywhere in the neighborhood. Every unknown neighbor is immediately white. The neighborhood size changes by position (corner 4, edge 6, interior 9) but the rule is always the same.

Clue = maximum — fill all neighbors

When a clue equals the total number of cells in its neighborhood, every cell must be black. Neighbourhood maxima: 4 at a corner, 6 on an edge, 9 in the interior.

Satisfied clue (turns green) — clear remaining unknowns

As soon as a clue turns green its count is exactly met. Every remaining unknown (grey) cell in its neighborhood must be white — clear them immediately.

Remaining unknowns = remaining count — fill all black

If a clue still needs N more black cells and has exactly N unknown neighbors left, every one of those unknowns must be black. This is the complement of the green-clue rule and is equally powerful.

Intermediate Patterns

Once you apply a basic pattern you will often satisfy an adjacent clue for free. These two rules let you read those consequences immediately.

Green clue — clear all remaining unknowns

The moment a clue turns green its count is exactly met. Every unknown cell still in its neighborhood must be white — clear them right away.

Example: filling the corner's 2×2 block places 4 black cells inside this left-edge cell's neighborhood, turning its clue of 4 green. The 2 unknowns at the top are forced white.

Satisfied edge clue cascades up — interior clue forces white row

A bottom-edge clue of 6 fills its entire 2×3 neighborhood (middle and bottom rows of the 3×3 view below) — that is the basic pattern applied once. The interior cell directly above it also has clue 6. Its 9-cell neighborhood now contains those same 6 black cells, so it too turns green immediately. Its top row of 3 unknowns must be white.

Remaining unknowns = remaining count — fill all black

If a clue still needs N more black cells and has exactly N unknowns remaining, every one of those unknowns must be black.

Example: a corner clue of 3 where one neighbor is already white. Three cells are still unknown; the clue needs exactly 3 more black. Fill all three.

Step-by-Step: Your First Solve

1. Scan every clue for an obvious pattern. Look for 0s (clear all neighbors), max-value clues (fill all neighbors), green clues (clear all remaining unknown neighbors), and clues where unknowns equal the remaining count (fill all). Apply every one you find before moving on.
2. Work corners and edges first. Their smaller neighborhoods (4 or 6 cells) mean their clues resolve more easily. A corner 3 out of 4 is tightly constrained; an interior 5 out of 9 has far more possibilities.
3. Use green clues to propagate. Filling or clearing cells near a clue can satisfy it. Once it turns green, every unknown in its neighborhood is forced white. That in turn may satisfy adjacent clues, creating a chain reaction.
4. Compare overlapping clues (subtraction technique). Adjacent cells share neighbors. If clue A = 5 and clue B = 3, and B's entire neighborhood is inside A's, then A must have A − B = 2 black cells in its exclusive (non-shared) neighbors. This narrows down which cells are black without any guessing.
5. Repeat until all clues are green. Every Mosaic puzzle on minesweeper.org is solvable by pure deduction. If you feel stuck, look for a clue whose remaining-unknown count equals its remaining-black count — that clue will unlock the next step.

Daily Puzzle vs. Random Mode

The Daily puzzle is the same for every player worldwide and resets at midnight UTC. Solve it to post your time to the global leaderboard.

Random mode generates a fresh unique-solution puzzle on demand — use it for extra practice or to keep playing after the daily is solved.

The Easy 5×5 mode at /mosaic is a beginner-friendly version with a smaller grid and simpler constraints — a good starting point before tackling the standard 9×9.