About Intermediate Sudoku
Intermediate Sudoku brings a real challenge. With fewer givens than Easy, these 9x9 puzzles reward careful logic and pattern recognition.
You will start using techniques like hidden singles and candidate elimination. Every puzzle still has a single unique solution and never requires guessing.
How to play Intermediate Sudoku
- Fill every empty cell with a digit so that each row contains the digits 1-9 with no repeats.
- Every column must also contain the digits 1-9 exactly once.
- Each of the nine 3x3 boxes must contain the digits 1-9 exactly once.
- Use the number pad or your keyboard to place a digit, and the Erase button to clear a mistake.
- The puzzle is solved when the whole grid is filled correctly.
Tips for Intermediate Sudoku
- Scan rows, columns and boxes for a digit that can only go in one place (a hidden single).
- Pencil in candidates for tricky cells and eliminate them as you place other numbers.
- Work from the most-filled regions outward - they give you the most constraints.
- Turn on Fast Mode to place the same digit across the board quickly.
Strategies and techniques for Intermediate Sudoku
Hidden singles
Within a row, column or box, check where a given digit can still go. If there is only one possible cell for it, place it there even if that cell has other candidates.
Pencil marks
Write small candidate numbers in each empty cell. As you place digits, cross candidates off. Organised pencil marks are the foundation of every advanced technique.
Locked candidates (pointing pairs)
When a digit's only spots inside a box all sit in one row or column, that digit can be removed from the rest of that row or column outside the box - and vice versa.
Why play Intermediate Sudoku?
- Sharpens logical thinking - every move is a small deduction that trains your brain to reason step by step.
- Boosts concentration and patience, since a single puzzle rewards sustained, focused attention.
- Improves working memory as you hold candidate numbers and patterns in your head.
- A calm, screen-friendly way to relax while still giving your mind a real workout.