Tangram Studio

How to play

Drag a piece from the tray into the grey outline, with a mouse or a finger. Let go near a corner and it snaps exactly into place. Use all seven, without overlapping and without anything sticking out.

With a keyboard, Tab reaches the board and 1 to 7 choose a piece. The arrow keys nudge it, the square-bracket keys turn it, F flips it and Escape puts it down.

The shape is judged by its geometry, so a solution that is not the one it was cut from still counts.

Rules and controls

• All seven tans are used in every shape. There are no spares.
• Pieces may be turned by eighths of a turn, and flipped over.
• No two pieces may overlap in a finished shape.
• No piece may stick out beyond the outline.
• Snapping puts a released piece exactly on a nearby corner. It can be turned off.
• Undo takes back one move at a time — U, or the button.
• A hint places one piece where it belongs: the one furthest from its place, not the first in the list.

Modes

• Guided — Pieces lock once they are right. Gentler shapes.
• Classic silhouettes — Nothing locks. The whole shape is judged at the end.
• Timed — Five minutes. Finish as many shapes as you can.
• Daily Shape — One shape a day, the same for everyone.
• Free Create — No target. Arrange the seven tans and keep what you make.

Tips

• Place the two large triangles first. They are half the area between them, so once they are down the rest of the outline is a much smaller problem.
• Look for the outline’s longest straight edge. A large triangle’s hypotenuse is the longest edge any tan has, and it usually belongs there.
• A sharp corner in the outline is a strong clue. Only a few of the tans have an angle that fits it, and often only one.
• If a piece will not quite fit, try flipping it before moving on — particularly the parallelogram, which is the only one that actually changes when you do.
• Turn snapping off if you want the harder version. Everything still works; you simply have to be accurate rather than close.

Privacy and local play

Everything runs in your browser. Your current arrangement, your settings and your best times are kept on this device only, and the button under the board clears them without touching any other Zerdly tool. No account, no sign-in, and nothing about your play leaves the machine you are on.

Questions

Where do the shapes come from?

They were generated here. Each one starts as the seven tans in their square and is made by picking a piece up and putting it down somewhere else that still touches the rest — so every shape is built out of real pieces and has an answer by construction. Seventy-two were kept out of ninety-three; the rest were discarded because a solver could not find their answer independently, and a shape that only the generator can solve is not a shape worth shipping.

Are these copied from a tangram puzzle book?

No. The tangram itself is centuries old and belongs to nobody, but every silhouette here was produced by the generator described above and none was traced from a printed set. That is also why they are shapes rather than cats and boats — a generated outline is honestly a shape, and calling it an animal would be a claim about what it looks like that nothing checked.

Does every shape have only one solution?

No, and the game is built around that. Most have several — swapping the two large triangles usually gives another — so completion is judged by measuring the arrangement rather than comparing it with a stored answer. If you fill the outline with all seven pieces and nothing overlaps, you have solved it, whether or not you found the arrangement it was cut from.

How close do I have to be?

Close enough that snapping can finish the job. Release a piece with one of its corners near a corner of the outline or of a piece already down, and it jumps exactly on to it. Without snapping, the shape is accepted when the total error is under about a sixteenth of a piece-width — tight enough that a visibly wrong arrangement is refused, loose enough that a careful hand is not.

What does Guided actually do?

It is the one mode that looks at the answer while you play. A piece that lands where the stored solution puts it is confirmed and locked, so a stray drag cannot knock it out again. That makes it easier, which is why Guided keeps its own best times rather than sharing Classic's — a locked-piece solve and an unassisted one are not the same result.

Why do the pieces sound different from each other?

The pitch of a placement is the size of the piece. A large triangle lands low and heavy, a small one light and quick, so you can hear which tan you just put down without looking away from the shape. The three steps match the three areas the seven tans actually have — the two large triangles sound identical because they are identical, and the rules treat them as interchangeable.

Can I flip a piece?

Yes, in every mode. It only changes the shape of the parallelogram — reflecting any of the other six gives you something a rotation would have given you anyway — but it is often the quickest way to get a triangle facing the way you want.

How does the daily shape work?

One shape a day, the same for everybody, taken from the UTC date rather than your local one. The rotation is a shuffled cycle rather than a random pick: every one of the shapes comes round exactly once before any of them repeats, and the order is reshuffled for the next cycle. Your results stay on this device.

What are the difficulty bands?

They are measured, not labelled. A solver records how much work finding a first answer costs and how many answers the shape has, and the bands are the thirds of that distribution. Counting answers alone does not work — too many shapes have exactly two — so the work is what separates them.

Is anything sent to a server?

No. The shapes, the solver, the hints, the sounds and your progress all run in your browser. There is no account, and clearing this game's data leaves every other Zerdly tool untouched.

Related interactives

• Block Fit — the other route about fitting shapes into a space, on a grid and against the clock of your own mistakes.
• Traffic Escape — sliding pieces on a crowded grid, with a way out to find.
• Path Pairs — join matching letters without crossing, and cover the board.
• Number Link — the same family on bigger boards, with a minimal-clue challenge.