Play Number regions puzzle (Filling) online Works — plays right here, unlimited puzzles
Guide updated October 2026 · Runs via WebAssembly (native port)
Filling is a number puzzle about areas. Some squares hold digits; you fill the rest so that every connected block of the same digit contains exactly that many squares. A 3 belongs to a group of three 3s, a 1 stands alone. The puzzle is ready below; click a square and type a digit, or drag to select several squares at once.
Controls — what does what
| Action | Keyboard | Mouse / touch |
|---|---|---|
| Fill a square | Move with arrows, type a digit | Click a square, type a digit |
| Fill several squares at once | Enter and arrows to select, Space to add/remove, then a digit | Drag across squares, then type a digit |
| Clear a square | 0, Space or Backspace | Click, then 0 or Backspace |
| Clear the selection | Escape | - |
| Undo / redo | U or Ctrl+Z / R or Ctrl+R | Game menu |
FREE This is the complete game, free. Open source under the MIT licence: the complete puzzle, with a new grid every time.
Filling is from Simon Tatham's Portable Puzzle Collection, © Simon Tatham and contributors, used under the MIT licence. Built from source by scripts/build-puzzles.mjs.
How to play
- Write a digit from 1 to 9 in every empty square.
- Each group of orthogonally connected squares holding the same digit must contain exactly that many squares.
- Squares touching only at a corner are not connected.
This means two 1s can never be side by side, and two separate groups of the same number can only touch diagonally.
Sizes and difficulty
The Type menu has three sizes: 9x7, 13x9 (the default) and 17x13. There are no difficulty settings; bigger grids simply take longer. Custom lets you set any number of rows and columns.
Solving tips
Fill any square boxed in by finished groups first: if it cannot join a neighbour, it is a 1. When two equal digits sit close together, check whether joining them would make the group too big; if so, the square between them must be something else. A clue with only one way out must extend that way. Large numbers like 7 or 8 near an edge often have only one shape that fits.
Where this puzzle comes from
Filling is part of Simon Tatham's Portable Puzzle Collection, a set of about forty logic puzzles written by Simon Tatham and contributors and released under the MIT licence. Every grid is generated on the spot, so the supply never runs out, and for the grid-logic puzzles the generator makes sure each has exactly one solution, reachable by reasoning rather than guessing. The version here is the collection's own code compiled to WebAssembly; the Game menu can save a puzzle to a file and load it again, and the Type menu changes the size and difficulty.
Frequently asked questions
Can two separate groups have the same number?
Yes, as long as they do not touch along an edge. If two groups of 4 shared an edge they would merge into one group of 8, which breaks the rule.
What is this puzzle called elsewhere?
It is a Nikoli puzzle published as Fillomino. Filling is the name used in Simon Tatham's collection, which generates fresh grids.
Is Filling free to play here?
Yes, with no limit on the number of puzzles. Filling is open-source software under the MIT licence, and every grid is generated fresh when you press New game.
Does it work on a phone or tablet?
Yes. A tap works as a click and the puzzle resizes to fit the screen. Puzzles whose controls use the right mouse button are easier with a mouse.
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Want a game like this on your own site?
Number regions puzzle (Filling) isn't ours to give away — we host it, we didn't write it. But eleven of the games here we did write from scratch, and those are free for anyone to put on their own page: one line of HTML, no account, no permission, no attribution beyond a credit line.