Free Daily Puzzle: Yunikumaka 10×10 (0028)

Yunikumaka (Unique Marker) is a logic puzzle invented by Naoki Inaba (Japan).

• The grid contains dots placed either inside cells or on borders between two neighboring cells. It may also contain black cells.

• Divide the grid into regions of exactly 4 cells each (tetrominoes).

Dots

• Each region must contain exactly one dot:

  • a dot in the center of a cell counts for the region containing that cell;

  • a dot on a border counts if that border lies inside the region (i.e., between two cells of the same region).

• Dots that lie on the border between two different regions are ignored.

Black cells

• Black cells do not belong to any region.

Solved by logic alone; the puzzle has a unique solution.