Press 'r' for randomness.
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Regenerate

View on a bigger screen for more control.

Subdivide

Subdivide the grid by a number.

Logic: The grid is divided into equal parts of cells, depending on the Subdivide By parameter. Next, each consecutive part of the cells is halved. For example, when Subdivide By "3" is selected, the grid is divided into three parts: cells fully filled, cells divided into 2×2 grid and cells divided into 3×3 grid. Random 50% of each subdivided cell is erased.

Use the Display Grid function for a better understanding of the process.