Hard sudoku puzzles that reward notes

Hard sudoku grids with 26 to 30 clues, each with one solution and rated as needing naked or hidden pairs, triples or box-line reduction. This is the level of the daily puzzle and the point where pencil marks start to matter. No app, no sign-up, no interstitial before you play; works offline and from the keyboard.

How to play hard sudoku

1. Same rules: every row, column and 3×3 box gets 1 to 9 once, from 26 to 30 givens.
2. Place the easy singles by scanning rows, columns and boxes.
3. Then press Fill notes, or turn on "Start with all notes filled in" in settings.
4. Look for pairs and triples in the notes and remove the candidates they rule out.
5. Hint explains elimination steps too: it shows the pair or triple, then the placement it unlocks.

Hard sudoku: what techniques you need

Every Hard grid needs at least one of five techniques on top of singles and pointing pairs. All of them remove candidates rather than place digits, so they only make sense with notes.

Naked pairs and triples

If two cells in a row, column or box both have exactly the candidates 3 and 8, those two digits are spoken for, and you can remove 3 and 8 from every other cell of that unit. A naked triple is three cells whose candidates together are only three digits, such as 2 5, 5 9 and 2 9. Not every cell needs all three.

Hidden pairs and triples

Now look by digit. If 1 and 6 can appear in only the same two cells of a box, those cells must be 1 and 6, and any other candidates in them can go. Scanning a unit digit by digit finds them.

Box-line reduction

The reverse of a pointing pair: if a digit’s candidates in a row or column all fall inside one box, the digit must be in that part of the box, so remove it from the rest of the box.

Where to look

Units with few empty cells hide the most pairs. After each elimination, recheck that unit for a naked or hidden single before searching elsewhere.

Daily, stats and printables

The timer starts on your first move and pauses when you switch tabs. Hard stats stay in your browser: played, won, win rate, best and average time. Undo and redo cover the whole game. The first two hints per puzzle are free; later hints may offer a short ad or a 30-second wait. A puzzle code such as A7K3Q (?p= in the address) replays the same grid, and the win panel gives a result to share.

The daily is a Hard grid unless you pick another level.

Plays anywhere, no app, no account

Hard sudoku notes stay readable on a phone, and every cell, note and hint is reachable from the keyboard. Tidy Puzzles runs entirely in your browser: there is no app to install, no account to create and no interstitial before you can play. After the first visit the game also works offline, because each puzzle is generated on your device from a seed. Every board can be played with the keyboard alone, on a phone or a desktop, and your stats and unfinished puzzles stay in this browser rather than on a server.