Sudoku Campaign

The campaign teaches sudoku the way solvers actually learn it: one technique at a time, in the order each builds on the previous. Every stage opens with a short tutorial pulled from the matching /strategies guide, then drops you into puzzles that genuinely require the technique you just learned. The campaign is free, no account needed to start; signing up saves your progress across devices.

Stages

1. 1

   Stage 1 — Naked Single

   The simplest move in sudoku: a cell with only one digit it can hold.

2. 2

   Stage 2 — Hidden Single

   Locked

   A digit confined to a single cell within a row, column, or box.

3. 3

   Stage 3 — Pointing Pair

   Locked

   A digit confined to one row or column inside a 3×3 box.

4. 4

   Stage 4 — Claiming Pair

   Locked

   A digit confined to one box inside a row or column.

5. 5

   Stage 5 — Naked Pair

   Locked

   Two cells holding the same two digits — those digits drop from every peer.

6. 6

   Stage 6 — Hidden Pair

   Locked

   Two digits hidden behind extra candidates in two cells.

7. 7

   Stage 7 — Naked Triple

   Locked

   Three cells whose combined candidates are exactly three digits.

8. 8

   Stage 8 — X-Wing

   Locked

   A 2×2 grid pattern eliminating across two rows and two columns.

Campaign progress saves automatically once you complete a stage. Signing up syncs progress across devices; without an account, progress saves locally in this browser.