Monster puzzle
AI Escargot
11.0SE grade
By The Hardest Sudoku Team · Last updated
1
7
9
3
2
8
9
6
5
5
3
9
1
8
2
6
4
3
1
4
7
7
3
The puzzle as published (23 clues). Solution not shown.
- SE grade
- 11.0
- Creator
- Arto Inkala
- Year
- 2006
Origin and lore
AI Escargot is Arto Inkala's puzzle (created 2006, later published as a book in 2007), named for the snail-shaped trail a solver traces through it. On release it was billed as the hardest Sudoku in the world and became the canonical reference for 'monster' difficulty, requiring chains well beyond singles and pairs.
Source: SudokuWiki.org (Escargot); Arto Inkala. Note: the corrected grid removes an erroneous clue at H3.