Custom Minesweeper

Understanding Mine Density

The feel of a board is driven more by mine density (mines ÷ total cells) than by raw size. A few useful reference points:

• ~12% — Beginner density. Lots of empty cascades, easy deduction. Good for warming up or learning.
• ~16% — Intermediate density. Chains get longer, overlapping constraints appear more often.
• ~21% — Expert density. Few zero-cells, nearly every reveal is a number. Logic-dense and unforgiving.
• >25% — Brutal. Short deduction chains everywhere. Many boards require guessing even with No Guess off.

Setting mines to about 15–20% of total cells places you in the sweet spot between "too easy" and "too chaotic." Go higher if you want to practice reading dense clusters; go lower if you want to practice long cascade management and speed.

Interesting Configurations

• 10×10, 15 mines (~15%) — A compact intermediate-feel board. Finishes fast, good for repetition training.
• 20×10, 30 mines (~15%) — Wide and shallow. Emphasises horizontal reading and edge constraints.
• 16×16, 40 mines (~16%) — Classic Intermediate dimensions. Use this if you want to practice the standard size without the official leaderboard pressure.
• 20×20, 80 mines (~20%) — A square Expert-density board. Bigger than Expert in area but still readable.
• 30×30, 135 mines (~15%) — Large intermediate board; excellent for practicing cascade management across a wide area.
• 5×5, 5 mines (~20%) — Tiny and brutal. Almost every solve involves a guess. Good for studying corner and edge constraint patterns in isolation.

No Guess on Custom Boards

No Guess mode is available for custom boards, but its success rate depends heavily on your configuration. The generator uses constraint propagation and retries up to 200 times to find a board solvable by logic alone.

• Low density (<15%) on larger boards works well — the solver finds valid layouts quickly.
• High density (>20%) makes No Guess harder to satisfy. The generator may exhaust its retries and fall back to a standard random board. You'll see no warning when this happens.
• Very small boards (under 6×6) have limited neighbor variance, so No Guess layouts are rare regardless of density.

For a reliable No Guess experience on custom dimensions, aim for 10–15% mine density on boards of at least 8×8.

Where to Go Next

• Beginner — 9×9, 10 mines. The classic starting point with a daily leaderboard.
• Intermediate — 16×16, 40 mines. The standard skill checkpoint.
• Expert — 30×16, 99 mines. The definitive benchmark.
• Cylinder — Custom-size boards where the left and right edges connect seamlessly.
• Toroid — All four edges connect — no corners, no edges, every cell has eight neighbors.
• Hexsweeper — Minesweeper on a hexagonal grid; six neighbors per cell instead of eight.