- Sudoku Variations
A well-researched article with a large collection of sudoku variants.
- Sudoku Puzzles
A large number of sudoku variants, including an 81x81 sudoku puzzle!
- Top Notch Two Doku
Two overlapping sudoku grids. One new puzzle per week. Basic online solver.
- Raetselmann.de
Several variants based on overlapping sudoku grids, including a monster based on 11 grids in the archive.
- Magic Sudoku
Magic Sudoku: still a 9x9 grid but extra constraints. One puzzle a day and more in the archive.
- Sudoku-like Puzzles
Daily sudoku-like puzzle. No online solving grid.
- Hexafex
Hexafex: a sudoku variant with a hexagonal board and triangular cells.
- Colour Sudoku
Colour Sudoku: a sudoku variant with nine colors.
