Shakashaka rules

Rules

Shakashaka rules: In some empty cells, shade a right triangle occupying exactly half the cell. All unshaded area must be rectangular. A number in a cell indicates how many rectangles are in the up to four cells orthogonally adjacent to the clue. In other words, there are five possibilities for each empty cells: leaving it empty or one of the four right triangles: ◢, ◣, ◤, ◥.

Example

Here is an example of a shakashaka grid and its solution.

Shakashaka example grid
Solution of shakashaka example grid

Solve online here.

Online solve

In order to solve Shakashaka puzzle on Penpa, either use the shape mode, and find the triangles in shape, or use the shakashaka in the Paint section of the Composite mode. In this mode, a left click put a dot in a cell, and a click while dragging toward one of the cell corner put a triangle filling this corner.

For automatic solution checking, place correctly all rectangles.

History of Shakashaka

Shakashaka is a puzzle type developed and published by Nikoli.

Masyu rules

Rules

Masyu rules: Draw a single, non-intersecting loops passing orthogonally by the center of some cells. The loop must pass by every circled cells. The loop must turn in all black circle, and must go straight in the cells just before and just after. The loop must go straight in all white circle and turn either just before or just after each white circle.

Example

Here is an example of a Masyu grid and its solution

Masyu exemple
Masyu exemple solution

Solve online here

History of Masyu

According to Wikipedia and WPC unofficial wiki, Masyu first appeared in Nikoli in 1999 in a version with only white circles. Then, in 2000 in the version we know today.