Daily Disjoint Groups Sudoku
The extra rule
Cells in the same position within each box hold 1 to 9.
Take the top left cell of all nine boxes. Those nine cells form an extra region and must hold 1 to 9. The same goes for the top middle cell of every box, and for all nine positions.
So the grid carries nine extra regions laid over the printed ones, shaded here when you select a cell. It is the same puzzle you know with a second lattice underneath it.
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 also a kropki sudoku, a xv sudoku, a greater than sudoku, a nonogram with hand drawn pictures, and 2048. All of them are on the games page, and the solvers for real objects are on the puzzle tools page.