01
Clue Count and Difficulty — 512-Puzzle Study
Medium and Hard both have a median of 25 clues in our 512-puzzle catalog. Compare the distributions, example puzzles and technique-based ratings.
Sudoku Slate research
Sudoku difficulty and solving techniques
Clue counts, solving steps and worked examples from our 512-puzzle catalog.
Read the study →
02
Where Singles Stop — 512-Puzzle Study
In our 512-puzzle catalog, Hard puzzles reach the first candidate elimination with a median of 39 empty cells on the fixed solving path. Follow a worked example.
512
puzzles in catalog v1
4 × 128
puzzles per grade
5
solving techniques
Research data
Download puzzle records, summary tables and the source code used for these studies.