What is a pentomino puzzle?
A pentomino puzzle asks you to fill a board completely with the twelve shapes you can make by joining five squares edge to edge. The pieces are named after the letters they resemble, F, I, L, N, P, T, U, V, W, X, Y and Z, and you may rotate and flip them freely.
The twelve pieces cover 60 squares in total, which is why they fit exactly into a 6×10, 5×12, 4×15 or 3×20 rectangle, or an 8×8 board with a 2×2 hole in the middle. Since mathematician Solomon Golomb named them in the 1950s, pentominoes have become one of the most widely played tiling puzzles in the world.
How do I place a piece?
Take a piece from the shelf on the right (below the board on a phone) and drag it onto the tray; it snaps to the nearest grid cells. A green dashed outline shows a spot where it fits, a red one shows an overlap or a spot that runs off the board.
Tap a piece once to rotate it 90 degrees clockwise, and press F or the flip button to mirror it. R and F also work while you are dragging, so you can line a piece up on the way. A placed piece can be dragged again to move it or to return it to the shelf, and the undo button steps back through your moves one at a time. When a piece fits, it lands with a wooden click and a little press, and when the last piece goes in the whole board sparkles.
How are the levels arranged?
There are 32 levels. Levels 1 to 20 are practice boards that grow from a 5×3 tray with 3 pieces to an 11×5 tray with 11 pieces, and from level 21 on you use all twelve pieces on the classic boards.
| Level | Board | Pieces | Known solutions |
|---|---|---|---|
| 1 to 3 | 5×3 | 3 | varies |
| 4 to 12 | 5×4, 5×5, 6×5 | 4 to 6 | varies |
| 13 to 20 | 7×5 up to 11×5 | 7 to 11 | varies |
| 21 | 6×10 | 12 | 2,339 |
| 22 | 5×12 | 12 | 1,010 |
| 23 | 4×15 | 12 | 368 |
| 24 | 3×20 | 12 | 2 |
| 25 | 8×8 with a centre hole | 12 | 65 |
| 26 to 32 | 8×8 variants, 10×7, 9×7, 11×6, 10×8 frame | 12 | varies |
Each practice board is built from a fixed seed, so a level always uses the same set of pieces. The classic boards have many answers, and finding any one of them completes the level. Levels up to 20 unlock one after another; the classic boards from level 21 are open from the start.
Can I get a hint when I am stuck?
Yes. Press the bulb button or H and the solver keeps the pieces you have already placed, works out the rest, and flies one piece into its correct spot. If your current layout can no longer be completed, the pieces shake and a message suggests undoing a move.
The solver is a backtracking search that tries every piece in the first empty cell and gives up at once when any isolated empty region is not a multiple of five squares, so even the 6×10 board takes well under a second. You can use as many hints as you like, but they count against your star rating.
How are times and stars scored?
Every level records the time from start to finish, and you earn three stars with no hints, two stars with one or two hints, and one star with more. The level screen shows your stars and which levels are still locked.
- Best records: solve a level again faster or with more stars and the record updates, with a new best banner on the result screen.
- Saving: records stay in this browser only and are never sent to a server.
- Sharing: the Share result button turns your level, time and stars into a picture card.
Tips for solving pentominoes faster
- Start in the corners and along the edges. Only a few shapes can sit in a corner, so your options narrow fastest there.
- Place the awkward pieces first, especially X and W. The X looks the same in every orientation and sticks out on all four sides, so if it is left for last there is usually nowhere to put it.
- Count the empty cells. If a separate empty region is not a multiple of five, that layout can never be completed, and undoing right away saves time.
- Save I and L for long gaps. The straight pieces are the best fillers for the narrow slots that remain near the end.
- Remember to flip. F, L, N, P, Y and Z change shape when mirrored, so if rotating does not help, try a flip.
Controls
- Touch or mouse: drag a shelf piece onto the tray and drag placed pieces to move them. Tap a piece to rotate it; the buttons at the top rotate, flip, undo, hint and open the level list.
- Keyboard: R or Space to rotate, Left arrow to rotate the other way, F to flip, Z to undo, H for a hint, Tab to pick the next piece, Esc for the level list. R and F also work mid drag.
The classic boards have many solutions, so a layout that differs from a picture in a book is not wrong. Records are kept in this browser only and disappear if you clear its storage.