Print these large
Hard puzzles need candidate lists, and candidate lists need space. One or two puzzles per page is the right choice — at four per page the cells are about 9 mm and there is nowhere to write nine small digits.
What these grids ask for
Locked candidates, naked pairs, hidden pairs and the occasional triple. Nothing here needs an X-Wing — that is expert territory.
Every puzzle has exactly one solution and a complete logical path to it, so if you are stuck on paper there is a move you have not seen rather than a grid that needs guessing.
Pencil, not pen
A hard grid will have you writing candidates and then removing them again. That is the technique working, not a mistake — but it means a pencil and a decent eraser make the difference between a tidy grid you can read and a mess you abandon.
A method for paper
- Scan first and place everything the opening gives you.
- Mark candidates for one band of three boxes, not the whole grid.
- Work that band until it stops producing placements, then move to the next.
- Only mark the whole grid if the band-by-band approach stalls everywhere.
Working in bands keeps your marks fresh — the ones you wrote ten minutes ago are the ones most likely to be out of date.
Common questions
How many clues do hard puzzles have?
Usually 24 to 30, with difficulty coming from the techniques required rather than the count alone.
Which techniques will I need?
Locked candidates and pairs or triples. The strategy guides cover all of them with worked examples.
Is guessing ever needed?
No. Grids that cannot be solved by technique alone are rejected when they are generated.
How long does a hard puzzle take on paper?
Twenty to forty-five minutes for most solvers, and longer if you mark candidates carefully as you go. That is normal for the difficulty rather than a sign of being slow.