Suguru

1. 1The grid is split into regions by thick lines. A region of two squares holds 1 and 2, a region of three holds 1, 2 and 3, and so on up to five.
2. 2Two squares that touch, even only by a corner, never hold the same digit.
3. 3Start with the small regions and with the squares next to many given digits. When you select a square, its region and its eight neighbours light up: those are the squares it must differ from.
4. 4Check my work marks the digits that are wrong. A hint fills in one square: it costs a little XP, never time.
5. 5There is a new puzzle every day, the same for everyone: easy from Sunday to Tuesday, medium from Wednesday to Friday, a big hard grid on Saturday. Every puzzle has one solution, found by logic alone.

Keyboard: arrows to move, 1 to 5 to write, N for notes, Backspace to erase, U to undo.