THE PLAYBOOK · QTHCC
How to play 4x4 Sudoku
Use QTHCC to play 4x4 Sudoku and read its instructions on the same page. Fill all cells with 1–4; do not repeat a symbol in any row, column or region. Follow the example-led learning approach for your next round.
Example-led learning
Read the worked example, identify its key decision, then look for a comparable decision while you play.
Your goal
Fill all cells with 1–4; do not repeat a symbol in any row, column or region.
Step by step
- Select an empty cell. The original clues cannot be edited.
- Choose a symbol from the number pad, or type it on a keyboard.
- Turn Notes on to record candidate symbols without committing an answer.
- Use Check entries to check your filled values. Hint reveals one value from the verified solution.
- Complete the board, or choose New puzzle for another board.
Controls
Tap or click a cell and use the number pad. Keyboard: arrows select cells; digits (and A–G on 16×16) enter values; Backspace erases.
A useful example
Before filling a cell, compare the symbols already used in its row, column and 2 × 2 region. A candidate must be absent from all three.
Watch out for this
Notes are reminders, not final entries. A full board only counts as complete when it satisfies every rule.
Common questions
Can you show a concrete example?
Before filling a cell, compare the symbols already used in its row, column and 2 × 2 region. A candidate must be absent from all three.
What is included in this edition?
A real 4 × 4 puzzle with 2 × 2 regions, candidate notes, undo and saved progress. Every included puzzle is checked for a unique solution.
Which controls should I use?
Tap or click a cell and use the number pad. Keyboard: arrows select cells; digits (and A–G on 16×16) enter values; Backspace erases.
