How to play Wedge Rooms

Put dark half-square triangles in some white squares so that every white area becomes a rectangle — upright or tilted 45° — and every number counts the triangles beside it. Also known as Shakashaka, Triangle rectangle puzzle.

▶ Play Wedge Rooms ⊞ Open the solver

The rules

A triangle fills half of a white square, with its right angle in one of the four corners.
Every white area (including the white halves of triangle squares) must form a rectangle, upright or tilted at 45°.
A number on a black square is how many of its four side neighbours hold a triangle.
Black squares never hold triangles.

Playing Wedge Rooms on Puzzle Solvers

Choose a size and a difficulty, then press New Puzzle.
Tap near a corner of a white square to put a dark triangle into that corner. Tap the same corner again for a dot (empty), again to clear.
Numbers turn green when they have exactly that many triangles beside them; corners that can’t work show in red.
Hint explains the next deduction — numbers, and how white parts must meet at every corner point.

Open the Wedge Rooms game →

Using the Wedge Rooms solver

Choose the size, click the black squares and type their numbers (or press Sample).
Press Solve and step through: numbers and corner points, one triangle at a time.

Open the solver →

A worked example

A 4 surrounded by white squares: all four neighbours hold triangles, each with its dark corner touching the black square’s sides.

Two white squares side by side between black squares: they must stay empty, or the white part would have a pointed 45° end.

Strategies

Zeros. A 0 means its neighbours are all empty white (or black).
Corner points. Where white parts meet at a grid corner they must make a right angle (90°) or a straight line — never 45° or 270°.
Diamonds. Four triangles around a point, each pointing outwards, make the smallest tilted rectangle.
Walls and edges. A triangle against the grid edge or a black square points its dark corner at it.
Big empties. An all-white upright rectangle needs no triangles inside — only its corners matter.

Common mistakes

Leaving a white area L-shaped — it must be a rectangle.
Making a white point of 45° where a triangle meets the edge.
Forgetting that tilted rectangles are allowed too.

Where it comes from

Triangle-rectangle puzzles were first published in Japan in 2008 and quickly became a favourite for their striking diamond-filled solutions.

Frequently asked questions

Can a white area be a tilted square?

Yes — rectangles tilted at 45° (diamonds) count, as long as all their corners are right angles.

Do numbers count diagonal neighbours?

No — only the four squares directly above, below, left and right.

Is there always one answer?

Yes — every puzzle here is checked to have exactly one solution.

How do I solve one from a book?

Open the Wedge Rooms Solver, mark the black squares and numbers, and press Solve.

Keep going

All guides: How to play every puzzle and game.