What is Sudoku?
I suggest Wikipedia for that one.
What is the number behind the difficulty?
The number in parentheses is the number of iterations (digits tested) needed to solve the puzzle after all the reducing methods have been applied — a decent proxy for how many guesses a human needs.
What is the start count?
The number of givens a puzzle starts with.
Can I link to a puzzle?
Of course. Every puzzle has a number: https://menneske.no/eng/sudoku?nr=100. Replace 100 with the puzzle number.
What is symmetric equal?
These sudokus are symmetric, and the symmetric digits are the same. They are very hard to generate, so there are not many of them.
What is push symmetric?
Something I invented, named by Simes. The symmetric boxes are B1→B9, B2→B8, B3→B7, B4→B6 — the symmetry applies between those boxes only.
May I write a program that downloads many puzzles?
No. If you want many puzzles, e-mail me first.
May I publish these puzzles?
No. This is a free service. If you want to publish puzzles you must buy them from me. See also copyright.