Here's another idea.In another thread, Princess Amy wrote: .... I'm working on a Clueless Jigsaw ....
Provide a completely filled-in 9x9 grid, but no grid lines. The object is then to figure out where the grid lines go, i.e. how to divide the 81 cells into nine 9-piece jigsaw pieces such that each piece contains each digit 1-9.
Presumably, the original row and column restrictions would have to be honored. Also, each piece would have to consist of nine contiguous cells (diagonal corner touches don't count). Also, you'd have to insist that no 9-cell piece coincides exactly with a complete row or column.
Can anybody come with a good puzzle along these lines? The idea is kind of like the Domino puzzles in another thread.