Daily Suguru
The rule
A block of n cells holds 1 to n, and touching cells always differ.
Each outlined block holds the digits 1 up to its own size, so a block of five holds 1, 2, 3, 4 and 5.
No two touching cells may hold the same digit, and touching includes diagonals. A digit blocks all eight squares around it, straight through block boundaries.
That second rule is the one that does the work. Place a 5 and the eight cells around it lose their 5 at once, which usually settles a neighbouring block.
Controls
Click a cell and type a digit, or use the pad. Space toggles pencil marks. Arrow keys move. Progress saves in this browser as you go, so you can come back to the same puzzle later today.
Solvable Without Guessing
Every puzzle here was generated and then handed to a solver that is only allowed techniques a person can use. If it could not finish the grid without a guess, the puzzle was thrown away rather than published. That also makes the answer unique, because every step it took was forced.
More to Play
There are twenty one daily sudoku variants, a 15 puzzle, peg solitaire and a nonogram with hand drawn pictures. For puzzles you can hold, see mechanical puzzles.