Filling

Filling is a logic puzzle where you complete a grid so that every number forms a connected region whose size exactly matches its value.

The goal of Filling puzzle is deceptively simple: fill the entire grid with numbers so that every orthogonally connected region of identical numbers has an area exactly equal to that number.

You start with a mostly empty grid containing a few pre-filled clues—numbers that indicate the size of the region they belong to. Your task is to deduce and fill in the rest of the grid, ensuring that:

• Each number n appears in a contiguous block (connected up/down/left/right) of exactly n cells.
• Regions of the same number must not touch, even at corners—only different numbers may be adjacent.
• The entire grid is completely filled with no blanks.

For example:

• A 1 must stand alone, surrounded by different numbers.
• A 3 must form a connected group of three cells (in an L-shape, straight line, or other valid configuration).
• No region may be larger or smaller than its number.

The puzzle requires careful spatial reasoning and constraint propagation. Often, the shape and position of existing clues force certain placements, and eliminating impossible configurations gradually reveals the unique solution.

To play Filling, start by selecting a puzzle type and size from the "Type" menu. Click "New" to generate a new puzzle.

Fill every blank square in the grid with a number. When the grid is complete, each orthogonally connected group of identical numbers must contain exactly as many squares as the number itself—for example, 1s must appear alone, 2s must form pairs, 3s groups of three, and so on.

To enter a number, click on a blank square to select it, then type the desired number using your keyboard. You can also drag to select multiple squares at once and type a number to fill all of them simultaneously. To erase numbers, select one or more squares in the same way and press Backspace.