Daily X Sudoku
The extra rule
Both long diagonals must also hold 1 to 9.
The two shaded diagonals are extra regions, exactly like a row or a box. A digit may appear only once along each of them.
It changes where the grid is tight: the centre cell sits on both diagonals, so it is the most constrained square on the board.
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 digit it placed was forced.
More to Play
There is a thermo sudoku, a killer sudoku, a nonogram with hand drawn pictures, and 2048. All of them are on the games page.