Using the touching rule

A number blocks all eight of its neighbors.

Each placed number rules itself out of the eight surrounding cells. In a region, that often leaves only one place for that number.

Two cells of a region that must hold 1 and 2 (in some order) block 1 and 2 from every cell touching both of them.

Combine the touching rule with region sizes: a 5 can only be in a 5-cell region.

Practise it

The Hint button on every puzzle explains the next step in the same plain language, so you can learn as you play. Play a Suguru puzzle.