- Code: Select all
`*-----------*`

|154|3..|9..|

|63.|5.1|84.|

|...|489|267|

|---+---+---|

|.73|926|...|

|84.|.7.|156|

|915|.3.|824|

|---+---+---|

|4.7|.18|5.9|

|569|..2|471|

|..2|.67|.83|

*-----------*

This could start from many possible initial clue sets, including the empty set. I expect anything between the min and max is achievable. So I don't think it's very interesting what potential range of unfillable cells a given set of clues has.

There are starting grids where the solution with the minimum number of unfilled cells is unique (the variant I proposed earlier in this thread). Such puzzles are very sudoku-like, and I'd love to see some. Unfortunately my current sudoku variant generator is not yet up to creating them.