First move the pieces to the desired position. You can't slay or castle. Checks should be resolved or in the last move.
Copy a 8x8 regular sudoku into the text area. Either completed or 0 for empty cells or 64 characters. 0 to 8 or whitespace.
Transpose or Load Grid depending on the orientation of the source sudoku.
Click on numbers to hide them in resulting chess sudoku.
Test intermediary set up with the Save/Test link.
Repeat last 2 steps until the sudoku has the desired level.
Save the resulting url for publishing.
Free 8x8 sudoku source
You can mouse select the solved sudoku first, and then overlay the unsolved version. Note the orientation!
The pieces carry the numbers that belong to the legal position of a certain game where each piece has at most been moved once.
Nothing is Slain and no Castling either.
Furthermore in each 2x4 box and on every row and column the numbers 1 to 8 must occur just once.