An example Toroidal Sudoku: the grid is a torus — the right edge wraps to the left and the top to the bottom, so a region can run off one side (arrows) and continue on the other.
Toroidal Sudoku treats the grid as a torus: the right edge wraps around to the left and the top to the bottom. Jigsaw regions can run off one side and continue on the other, so a single region may span the grid's edges as if they were joined.
The rule: the grid wraps around
Rows, columns and regions all still need 1–9, but regions may wrap across the borders. Below, one region (purple) exits the right edge and re-enters on the left — the two shaded strips are the same wrapping region.
A region wrapping the edges: the cells on the right and left belong to one region across the torus.
Solving strategy
- Follow regions across the edges. A region leaving one side continues on the opposite side.
- Scan wrapping units as one. Treat the two edge strips of a wrapping region as a single region for 1–9.
- Mind the wrap on lines too. Some variants wrap the row/column logic as well — check the puzzle.
- Feed the grid. Each digit placed behaves like a given for its row, column and (wrapping) region.
Common mistakes
- Treating the edges as walls. On a torus the borders join — regions and (sometimes) lines continue across.
- Splitting a wrapping region. The edge strips are one region and share the 1–9 requirement.
- Ignoring the ordinary rules. Rows, columns and regions still need 1–9.
Can I play it here?
Not yet — Toroidal Sudoku isn't one of the puzzle types SudokuStreak generates for now. But you can learn its rules above, and there's plenty here to sink your teeth into meanwhile:
- Try the closely related Classic, which you can play right now.
- Browse all the Sudoku variants we do offer.
- Or print free puzzles from the printable PDF page.