Oh wait Level 0, I thought vince was pulling my leg.
There is a Level 0 and it does have a purpose. You start with a completed puzzle and switch to Make mode and then design your puzzle from that. Whether the puzzle has a unique solution or not is not as important as having an interesting design to show.
It's been so long since I worked the code, I think I forgot even then to make this option known on the first page.
Here is another designer Sudoku:
There is a Level 0 and it does have a purpose. You start with a completed puzzle and switch to Make mode and then design your puzzle from that. Whether the puzzle has a unique solution or not is not as important as having an interesting design to show.
It's been so long since I worked the code, I think I forgot even then to make this option known on the first page.
Here is another designer Sudoku: