Master the Grid
Sudoku Skills: Master the Grid
Master the Grid
Sudoku Skills: Master the Grid
Learn the app workflow, board controls, walkthroughs, and Full Access tools.
You will learn: the fastest way to choose a puzzle, enter values, use notes, and review the logic behind each move.
Sudoku Skills is built as a tutor. You still do the solving, but the app can explain the reasoning behind each step, check your work, and help you practice human techniques in order.
Start from the header menu, choose a puzzle source, and click an empty cell. Use Value mode for final answers and Notes mode for candidate marks. When you are unsure, use Nudge for coaching or Solve for the completed board. Full Access adds technique board animations inside the walkthrough.
With Full Access, replay the timeline after Solve. The strongest learning happens when you compare what you tried with the clean proof the walkthrough shows.
What to notice: The app is built around learning. Every action either helps you solve or helps you review how the puzzle was solved.
You will learn: where the setup actions live so the board can stay focused on solving.
The fixed header keeps navigation available without taking space from the board. Use the Tools menu for Sudoku School, Puzzle Library, Saved puzzles, Statistics, PDF Book, Sudoku OCR, Help, Account, and the platform-specific install action.
Access status now lives on the Account page instead of the header. Basic is the visitor demo experience with Daily Puzzle and Beginner Random Puzzle. Limited is the signed-in free experience with the core solver, saved progress, Solve, Nudge, history, and stats. Full is the monthly or annual membership tier for technique board animations, the curated Puzzle Library, Sudoku School, badges, the Sudoku Skills Diploma, OCR, and printable PDF Books.
Install options adapt to the platform. Chromium browsers can show Install App. iOS shows Add to Home Screen instructions.
What to notice: Tools menu items now open app sections in the page instead of full-screen overlays. OCR stays board-adjacent because scan review is part of importing a puzzle image.
You will learn: how blank, Daily, random, curated, and saved sources differ.
Open Puzzle Library from the header menu. Basic visitors can play today's Daily Puzzle and generate a Beginner Random Puzzle. Limited users add Blank Puzzle and higher random difficulties. Full Access unlocks the curated Library by difficulty and tags.
Curated Library, Daily, and School puzzles auto-track progress for signed-in users. They do not use the Save button because they already know where they came from.
Daily puzzles are generated by date and scheduled difficulty. The app displays the actual difficulty the puzzle earns from the human-technique engine; it does not relabel a puzzle to fit the calendar.
What to notice: Puzzle Library starts official puzzles and resumes official progress automatically. Saved puzzles is only for puzzle states you intentionally save to your personal account library.
You will learn: the board language used by Help, Nudge, School, and walkthroughs.
A Sudoku grid has 9 rows, 9 columns, and 9 boxes. Every row, column, and box must contain digits 1 through 9 exactly once.
Cells are named by row and column. R4C1 means row 4, column 1. Givens are the starting clues; they are locked and styled differently so you know they cannot be changed.
You do not need to memorize box numbers. The app shows coordinates when they help explain a move.
What to notice: Box numbers run left to right and top to bottom. R4C1 is the first cell in row 4 and belongs to box 4.
You will learn: how to use the board, number pad, keyboard, Clear, and Enter without muddying your recorded path.
Select an editable cell, then use the number pad or keyboard to enter a value. Use Clear, Backspace, or Delete to remove an editable value.
Press Enter to commit the current cell. This helps the manual replay record your final decision for that cell instead of every intermediate correction.
On mobile, the same actions are available through larger touch targets. Timelines and recent lists are designed to scroll horizontally when space is tight.
What to notice: The number pad and keyboard do the same thing. Enter commits the selected cell and keeps focus where it is.
You will learn: why candidate notes are the foundation for medium, advanced, and expert solving.
A candidate is a digit that can still legally fit in an empty cell. Notes let you keep those possibilities visible instead of trying to hold them in memory.
Use the Notes pill for pencil marks, or hold Shift while pressing a number to enter a temporary note. Tap the same note again to remove it.
Clean notes make techniques possible. Pairs, triples, locked candidates, fish, coloring, chains, and What-If proofs all depend on knowing which candidates remain and which candidates can be removed.
What to notice: Notes appear as small marks inside the cell. Tapping the same number again removes that note.
You will learn: how to see the row, column, and box that constrain one cell.
Blue hatches are cell-focused. They mark every peer of the selected cell: same row, same column, and same 3x3 box.
Use Blue Assist when you are asking, "What numbers are ruled out for this cell?" It is especially helpful while learning candidates and singles.
If a red circle appears on a blue-hatched value, your selected value would immediately duplicate a peer.
What to notice: The blue hatches instantly reveal every cell that shares R7C9's row, column, or box. Those are the cells that can rule numbers out for R7C9.
You will learn: how to scan possible homes for one digit.
Yellow hatches are value-focused. They appear when the selected cell already has a number and show open peer cells affected by matching values elsewhere.
Use Yellow Assist when you are asking, "Where can this digit still go?" That question is the heart of hidden singles and many later techniques.
Yellow does not mean wrong. It means the selected value is being compared against the rows, columns, and boxes of matching values on the board.
What to notice: Yellow hatches show the selected cell's nearby row, column, and box cells that existing 9s block, including R7C8 and R7C9, which are affected through a matching 9's box.
You will learn: how the board shows an immediate rule violation.
Red circles mark copies of the selected number. When a red circle appears on a blue-hatched peer, the selected value duplicates a number in the same row, column, or box.
Use Red Assist as a quick visual warning. It tells you which existing value conflicts with the value you are trying to place.
For technique walkthroughs, the app no longer circles unrelated filled values in purple. Purple focus now points to the actual technique evidence.
What to notice: R7C1 is both blue-hatched and red-circled because it is in the same row as the selected cell and already contains 7. That red circle is the immediate warning that entering 7 in R7C9 violates the board.
You will learn: the difference between validation and a learning nudge.
Validate checks whether your current entries conflict with the known solution or with Sudoku rules. It is most useful for manual or imported puzzles where the app needs to confirm the givens and your entries.
Nudge is coaching. It uses the human-technique engine to name a next logical idea, point to useful cells or candidate removals, and keep the final decision in your hands.
Use Nudge when you have stared at the board long enough that you are no longer learning. Use Solve when you want the completed board. Full Access adds board animations for supported human-technique steps.
What to notice: R4C1 should be 1. If 4 is entered there, Validate marks that exact cell red and leaves the givens alone.
What to notice: A correct manual entry is left alone. Validate focuses attention only on cells that need fixing.
What to notice: Nudge does not change the board. It names a human technique, explains what to look for, and points to the next placement or candidate elimination so your solve remains yours.
You will learn: how OCR review protects the puzzle before it reaches the board.
Choose Sudoku OCR from the header menu. The browser detects the grid and reads likely digits, then shows a review grid before anything is imported.
Correct uncertain or conflicting cells in the review grid. Validation then checks the reviewed givens for Sudoku consistency, enough clues, and a unique solution before the puzzle becomes playable.
Sudoku OCR is a Full access feature. The image-reading step is designed to speed up entry, not replace your review.
What to notice: Scan import is conservative. It speeds up entry, but the app asks you to confirm anything uncertain before the puzzle becomes a locked set of givens.
You will learn: how Solve turns a puzzle into named human-technique steps.
Solve completes the puzzle. For signed-in users, Solve opens a step-by-step walkthrough where each step names the technique, explains the reason, and highlights the cells or candidates that prove the move. Full Access adds board animations for supported human-technique steps.
For named techniques, use View Board Animation to watch the pattern play out on the board. You can play, pause, reset, or step frame by frame with the previous and next controls.
If you solve manually, Sudoku Skills records your committed entries and can replay your own path after the final correct value.
R4C1 has candidates 1, 4, and 8. But in box 4, only 1 can go in R4C1.
Technique: Hidden Single in a boxWhat to notice: The walkthrough title tells you the placement. The reason explains why that value is now safe.
You will learn: why expert puzzles sometimes require a controlled branch.
Strong solvers do not guess across the whole board. They choose a small uncertainty and follow its consequences.
The goal is to find a contradiction, a forced placement, or proof that a candidate can be removed.
This is still human reasoning. The guess is limited, tracked, and explained.
What to notice: The guess is limited and testable. The app records what happens so you can learn from the branch.
You will learn: how to explore a branch without damaging the real puzzle state.
What-If mode lets you ask, "What would happen if this candidate or combination were true?"
The app saves the decision board, follows the branch, and keeps the main solve safe.
Use What-If as a training gym for chains, contradictions, and capstone School lessons.
What to notice: Both cards show box 3 only. Purple cells are the values being tested in that combination, matching the live What-If cards.
You will learn: what gets saved manually, what auto-resumes, and what requires a connection.
Basic access is the visitor demo experience with Daily Puzzle and Beginner Random Puzzle. Limited access is the signed-in free experience with the core solver, advanced random puzzles, Validate, Solve, Nudge, Save, Saved puzzles, history, and stats. Full access is the monthly or annual membership tier for technique board animations, the curated Puzzle Library, Sudoku School, badges, the Sudoku Skills Diploma, PDF Book generation, and Sudoku OCR.
Use Save for puzzles you create yourself or random puzzles you want to keep in your personal Saved puzzles library. School, curated Library, and Daily puzzles auto-track progress and do not use the Save button.
If you make real progress on a Daily Puzzle and do not finish before the next Daily appears, it can move to Saved puzzles as an unfinished old Daily. Opening the Daily without entering anything does not create a saved rollover puzzle.
The installed app shell can load offline, but account actions, sync, Daily Puzzle, random generation, OCR validation, Nudge, Solve, and other server-backed actions require a connection.
What to notice: Save creates a personal Saved puzzles entry. Official Library, Daily, and School puzzles resume automatically without using Save. Unfinished old Daily Puzzles with progress move into Saved puzzles automatically when the next Daily appears.
You will learn: the words used by Help, School, Nudge, walkthroughs, and board animations.
Each term below answers the same learning question: what is it, why does it matter, and how does Sudoku Skills show it?
Common beginner mistake: checking only a row or column and forgetting the box. Every placement must satisfy all three: row, column, and box.