You have a grid of squares, some of which contain digits, and the rest of which are empty. Your job is to fill in digits in the empty squares, in such a way that each connected region of squares all containing the same digit has an area equal to that digit.

(‘Connected region’, for the purposes of this game, does not count diagonally separated squares as adjacent.)

For example, it follows that no square can contain a zero, and that two adjacent squares can not both contain a one. No region has an area greater than 9 (because then its area would not be a single digit).

Credit for this puzzle goes to Nikoli [14].

Filling was contributed to this collection by Jonas Kölker.

[14] http://www.nikoli.co.jp/en/puzzles/fillomino.html

29.1 Filling controls

To play Filling, simply click the mouse in any empty square and then type a digit on the keyboard to fill that square. By dragging the mouse, you can select multiple squares to fill with a single keypress. If you make a mistake, click the mouse in the incorrect square and press 0, Space, Backspace or Enter to clear it again (or use the Undo feature).

You can also move around the grid with the cursor keys; typing a digit will fill the square containing the cursor with that number; typing 0 will clear it. You can also select multiple squares for numbering or clearing with the return and arrow keys, before typing a digit to fill or clear the highlighted squares (as above). The space bar adds and removes single squares to and from the selection. Backspace and escape remove all squares from the selection.

(All the actions described in section 2.1 are also available.)

29.2 Filling parameters

Filling allows you to configure the number of rows and columns of the grid, through the ‘Type’ menu.