Daily Palindrome Sudoku
The extra rule
Every line reads the same in both directions.
The first cell of a line equals the last, the second equals the second from the end, and so on inward.
It is the gentlest marking here and the most useful: a palindrome simply copies a digit from one part of the grid to another, often across a box boundary where nothing else would connect them.
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.